JP2005232435A - Heat-shrinkable film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable film which is preferably used for an application such as shrinkable packaging, shrinkable bundling packaging, shrink label or the like, and in particular excellent in balance of heat shrunken finish, natural shrinkage, transparency, film stiffness(rigidity at ordinary temperature) and mechanical strength such as resistance to breakage. <P>SOLUTION: The heat-shrinkable film is a heat-shrinkable film which is obtained by at least unidirectionally stretching a mixed resin composition composed of a polycarbonate-based resin and a polyester-based resin that can shift the glass transition temperature resulted from the polycarbonate-based resin to a low temperature side, and has the heat shrinkage percentage of at least 20 % at least in one direction when dipped in water at 80°C for 10 sec, wherein the peak of the loss tangent(tanδ) curve measured at a vibration frequency of 10 Hz by dynamic viscoelasticity measurement is existed as a single peak in the range of not lower than 70°C and not higher than 130°C, and the half width of the loss tangent curve is not lower than 15°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-shrinkable film, a shrinkable label using the heat-shrinkable film, and a package. More specifically, the present invention is suitably used for applications such as shrink wrapping, shrink tying wrapping, and shrink labels, and particularly shrink finish, natural shrinkage, transparency, film waist (rigidity at room temperature), rupture resistance, etc. The present invention relates to a heat-shrinkable film having an excellent balance of mechanical strength, a shrinkable label using the film, and a package equipped with the label.

  Currently, heat-shrinkable films widely used for shrink-wrapping, shrink-bound packaging, shrink labels for plastic containers, anti-fracture wrapping for glass containers, and cap seals are polyvinyl chloride films, polyester films, and polystyrene. System films have been put into practical use. The main characteristics required for heat-shrinkable films include shrinkage finish, spontaneous shrinkage (slightly higher than normal temperature, for example, the film shrinks slightly before its original use in summer), and transparency. Properties, mechanical strength such as film stiffness (rigidity at room temperature), rupture resistance, and the like. However, in recent years, in addition to these characteristics, the film is strongly demanded from the market because it is an environmentally-friendly material and responds to the Containers and Packaging Recycling Law. Yes.

  Although the polyvinyl chloride film has excellent practical properties and cost as a heat-shrinkable film, there is a possibility of generating chlorine-containing gas when incinerated after disposal. In addition, polyester film has strong elasticity, small natural shrinkage ratio, and excellent transparency, but still has problems in shrink finish, and shrinkage spots and wrinkles are likely to occur during heat shrinkage. Had. Polystyrene film is mainly made of styrene-butadiene block copolymer, and the shrink finish is very good, but the film is weak, the natural shrinkage ratio is large, and the fracture resistance is poor. Had.

  Among these problems, as a method for improving the shrink finish of the polyester film, for example, 5% by mass of an aromatic polycarbonate resin is added to a polyethylene terephthalate polymer having a glass transition temperature (Tg) of 40 ° C. to 80 ° C. A method of slowing the shrinkage after the shrinkage start temperature to broaden the heat shrinkage temperature range by blending and molding 10% by weight or less (see, for example, Patent Document 1), or a polyester resin having a glass transition temperature (Tg) of 40 ° C. or higher. A heat-shrinkable film in which a resin having a glass transition temperature (Tg) of 20 ° C. or more, for example, a polycarbonate resin is mixed in an amount of 1 to 50 parts by mass with respect to 100 parts by mass has been proposed (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 5-25294 JP-A-4-50238

  However, these heat-shrinkable films still have insufficient shrink finish and have not yet satisfied the market demand. In these heat-shrinkable films, an aromatic polycarbonate resin is mixed as a method for improving the shrink finish of the polyester film, but the mixing amount of the aromatic polycarbonate resin generally exceeds 30% by mass. In addition, the transparency and stretchability of the film are reduced, and the low temperature shrinkability (for example, the thermal shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds) is problematic.

  The present invention is for solving the above-mentioned problems of the prior art, and the object of the present invention is suitably used for applications such as shrink wrapping, shrink tying wrapping and shrink wrap labels, and in particular, shrink finishing, natural shrinkage. An object of the present invention is to provide a heat-shrinkable film excellent in balance of mechanical strength such as transparency, film stiffness (rigidity at room temperature), and fracture resistance.

  Another object of the present invention is a shrink label using a heat shrinkable film excellent in balance of mechanical strength such as shrink finish, natural shrinkage, transparency, film stiffness (rigidity at room temperature), and fracture resistance. And providing a package with the label attached thereto.

  As a result of intensive studies, the present inventors have found that a heat-shrinkable film obtained by stretching a mixed resin composition composed of a polycarbonate resin and a specific polyester resin in at least one direction can solve the above problems. The invention has been completed.

That is, the object of the present invention is achieved by the following heat-shrinkable film.
(1) A mixed resin composition comprising a polycarbonate resin and a polyester resin that shifts the glass transition temperature derived from the polycarbonate resin to a low temperature side is stretched in at least one direction and immersed in warm water at 80 ° C. for 10 seconds. The heat shrinkage rate is at least 20% in at least one direction, and the peak of the loss tangent (tan δ) curve measured at a vibration frequency of 10 Hz by dynamic viscoelasticity measurement is 70 ° C. or higher and 130 ° C. A heat-shrinkable film characterized by being present as a single peak in a range of 0 ° C. or lower and having a half-value width of 15 ° C. or higher of the loss tangent curve.
(2) The heat-shrinkable film according to (1), wherein the polycarbonate resin is an aromatic polycarbonate resin.
(3) A film obtained by stretching a mixed resin composition composed of 30% by mass to 70% by mass of an aromatic polycarbonate resin and 30% by mass to 70% by mass of a polyester resin in at least one direction, the polyester The system resin contains, as a carboxylic acid monomer (I) unit, an aromatic dicarboxylic acid of 80 mol% or more and 100 mol% or less in the total carboxylic acid monomer (I) unit, and a glycol monomer (B). ) As a unit, polyalkylene glycol 0.5 mol% or more of 1,4-cyclohexanedimethanol 0.1 mol% or more and 40 mol% or less and number average molecular weight 500 or more and 3000 or less in all glycol monomer (b) units Consists of structural units containing 15 mol% or less, and the thermal shrinkage when immersed in 80 ° C. warm water for 10 seconds is at least in one direction, A heat-shrinkable film characterized by being 20% or more.
(4) The glass transition temperature of the mixed resin composition measured by differential scanning calorimetry at a heating rate of 10 ° C./min shows a single value, and the glass transition temperature of the aromatic polycarbonate resin and the polyester system The heat-shrinkable film according to (2) or (3), which is between the glass transition temperature of the resin.
(5) The heat-shrinkable film according to any one of (1) to (4), wherein the glass transition temperature of the mixed resin composition is 50 ° C. or higher and 100 ° C. or lower.
(6) The heat-shrinkable film according to any one of (1) to (5), wherein the glass transition temperature of the polyester resin is 0 ° C. or higher and 50 ° C. or lower.

  Another object of the present invention is achieved by a shrinkable label using the heat-shrinkable film according to any one of (1) to (6) above and a package equipped with the shrinkable label.

  According to the present invention, it is suitably used for applications such as shrink wrapping, shrink tying wrapping, and shrink labels, and in particular, machines such as shrink finish, natural shrinkage, transparency, film waist (rigidity at room temperature), and break resistance. Heat-shrinkable film having an excellent balance of mechanical strength.

  In addition, according to the present invention, a shrinkage label excellent in balance of mechanical strength such as shrinkage finish, natural shrinkage, transparency, film waist (rigidity at room temperature), rupture resistance, etc., and a package equipped with the label Can provide.

Hereinafter, the heat-shrinkable film, shrinkable label, and package of the present invention will be described in detail.
It should be noted that the upper and lower limits of the numerical range in the present invention are those of the present invention as long as they have the same operational effects as those in the numerical range even if they are slightly outside the numerical range specified by the present invention. It is included in the equivalent range.

[Heat shrinkable film]
The heat-shrinkable film of the present invention is obtained by stretching a mixed resin composition composed of a polycarbonate resin and a polyester resin that shifts the glass transition temperature derived from the polycarbonate resin to a low temperature side in at least one direction, A heat shrinkable film having a heat shrinkage rate of 20% or more in at least one direction when immersed in a film for 10 seconds, and has a peak loss tangent (tan δ) curve measured at a vibration frequency of 10 Hz by dynamic viscoelasticity measurement. It exists as a single peak in the range of 70 ° C. or higher and 130 ° C. or lower, and the half width of the loss tangent (tan δ) curve is 15 ° C. or higher.
In the present specification, the half-value width of the loss tangent (tan δ) curve is the temperature difference between the low temperature side and the high temperature side, which indicates a value half of the loss tangent (tan δ) value at the maximum peak temperature of the loss tangent (tan δ) curve. The absolute value of The peak temperature of the loss tangent (tan δ) curve refers to a temperature at which the first derivative of the amount of change with respect to the temperature of the value of tan δ becomes zero.

  In the heat-shrinkable film of the present invention, it is important that the loss tangent (tan δ) curve peak obtained by dynamic viscoelasticity measurement first exists as a single peak shape in the range of 70 ° C. or higher and 130 ° C. or lower. If the peak temperature of the loss tangent (tan δ) curve is 70 ° C. or higher, it is possible to suppress an increase in the natural shrinkage rate, to obtain good dimensional stability, and to cause excessive shrinkage due to temperature rise during film mounting. This is preferable for practical use. On the other hand, if the peak temperature of the loss tangent (tan δ) curve is 130 ° C. or lower, it is preferable because the heat shrinkability defined in the present invention can be imparted without lowering the low-temperature stretchability. In the present invention, the peak temperature of the loss tangent (tan δ) curve is preferably 75 ° C. or higher, more preferably 80 ° C. or higher, and 125 ° C. or lower, more preferably 120 ° C. or lower.

  Next, in the heat-shrinkable film of the present invention, it is important that the half width of the loss tangent (tan δ) curve is at least 15 ° C. In the present invention, the half width of the loss tangent (tan δ) curve is 15 ° C. or higher, preferably 17 ° C. or higher, and more preferably 20 ° C. or higher. If the half-value width of the loss tangent (tan δ) curve is 15 ° C. or more, moderate compatibility can be obtained with almost no decrease in transparency, and good shrink finish of the heat-shrinkable film can be maintained. . On the other hand, the upper limit of the full width at half maximum of the loss tangent (tan δ) curve is not particularly limited, but it is 40 ° C. or less from the viewpoint of preventing a decrease in the transparency of the film due to a decrease in compatibility between the polycarbonate resin and the polyester resin. The temperature is preferably 35 ° C. or lower, more preferably 32 ° C. or lower, and most preferably 30 ° C. or lower.

  In the present invention, the peak of the loss tangent (tan δ) curve is present as a single peak shape in the range of 70 ° C. or higher and 130 ° C. or lower, and the half width of the loss tangent (tan δ) curve is 15 ° C. or higher. It is desirable to use a mixed resin composition having a peak temperature and a half-value width of a loss tangent (tan δ) curve in the same range as the film. That is, a polycarbonate resin and a predetermined polyester resin that shifts the Tg derived from the polycarbonate resin to the low temperature side are mixed, and the mixing mass ratio of these resins and the degree of compatibility thereof are adjusted to a predetermined range. Thus, the peak temperature and half-value width of the loss tangent (tan δ) curve of the entire mixed resin composition can be made to coincide with the ranges defined in the present invention. For example, in the case of using a polycarbonate resin having a relatively high Tg, by containing a relatively large amount of a polyester resin that shifts the Tg to the low temperature side, the Tg of the entire mixed resin composition is lowered, and a rapid heat By suppressing the shrinkage, the peak temperature and half width of the loss tangent (tan δ) curve can be adjusted within the range of the present invention.

  In the present invention, the loss tangent (tan δ) curve peak temperature and its half-value width obtained by dynamic viscoelasticity measurement can be measured under the following conditions. That is, a sample was cut into a length of 4 mm and a width of 60 mm, using a viscoelastic spectrometer DVA-200 (manufactured by IT Measurement Co., Ltd.), vibration frequency 10 Hz, strain 0.1%, heating rate 3 ° C./min, between chucks Measurement of storage elastic modulus (E ′) and loss elastic modulus (E ″) was started from −50 ° C. in the transverse direction under the condition of 25 mm, and loss tangent (tan δ = E ″ / E ′) curve was obtained from the obtained data. The peak temperature and its half-value width were obtained.

  The loss tangent value at the peak temperature of the loss tangent (tan δ) curve of the heat-shrinkable film of the present invention is not particularly limited, but when an amorphous polyester resin or a relatively low crystalline polyester resin is used. It is preferably 1.5 or less, more preferably 1.4 or less, and even more preferably 1.2 or less.

Next, the polycarbonate resin used in the present invention and the polyester resin that shifts the glass transition temperature derived from the polycarbonate resin to the low temperature side will be described.
<Polycarbonate resin>
The polycarbonate resin used in the present invention is not particularly limited as long as the peak temperature of the loss tangent (tan δ) curve can be in the range of 70 ° C. or higher and 130 ° C. or lower when mixed with the polyester resin described later. Various polycarbonate resins can be used. The polycarbonate resin may be either homopolycarbonate or copolycarbonate. Preferably, it is an aromatic polycarbonate resin, and may be either a branched structure or a linear structure, or a mixture of a branched structure and a linear structure.

  The aromatic polycarbonate resin that can be used in the heat-shrinkable film of the present invention can be produced using a known method such as a phosgene method, a transesterification method, or a pyridine method. As an example, a method for producing an aromatic polycarbonate resin by an ester exchange method will be described below.

  The transesterification method is a production method in which a divalent phenol and a carbonic acid diester are added with a basic catalyst, and further an acidic substance that neutralizes the basic catalyst is added to perform melt transesterification polycondensation. Representative examples of the dihydric phenol include bisphenols, and 2,2-bis (4-hydroxyphenyl) propane, that is, bisphenol A is particularly preferably used. Further, part or all of bisphenol A may be replaced with other dihydric phenols. Other dihydric phenols include hydroquinone, 4,4-dihydroxydiphenyl, bis (4-hydroxyphenyl) alkanes such as bis (4-hydroxyphenyl) methane and 1,1-bis (4-hydroxyphenyl) ethane, Bis (4-hydroxyphenyl) cycloalkane such as 1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, Compounds such as bis (4-hydroxyphenyl) ether, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane Alkylated bisphenols, 2,2-bis ( , May be mentioned 5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro-4-hydroxyphenyl) halogenated bisphenols such as propane.

  Representative examples of carbonic acid diesters include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (biphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, and the like. Can be mentioned. Of these, diphenyl carbonate is particularly preferably used.

  The weight average molecular weight of the aromatic polycarbonate resin used in the present invention is usually a lower limit of 10,000 or more, preferably 20,000 or more, and an upper limit of 100,000 from the balance between mechanical properties and moldability. In the following, preferably 50,000 or less is used. If the weight average molecular weight is 10,000 or more, the mechanical strength of the resulting aromatic polycarbonate resin does not decrease, and if the upper limit is 100,000 or less, an appropriate melt viscosity can be obtained. Since processability can be maintained and polymerization can be performed in a relatively short time, it is preferable from the viewpoint of production cycle and cost. In the present invention, aromatic polycarbonate resins may be used alone or in admixture of two or more.

<Polyester resin>
Next, the polyester resin used in the present invention will be described.
The polyester resin used in the present invention is not particularly limited as long as the Tg derived from the polycarbonate resin can be shifted to the low temperature side. Among them, as the carboxylic acid monomer (A) unit, the total carboxylic acid monomer (I) unit contains 80 to 100 mol% of the aromatic dicarboxylic acid, and as the glycol monomer (B) unit. 1,4-cyclohexanedimethanol 0.1 mol% or more and 40 mol% or less and polyalkylene glycol having a number average molecular weight of 500 or more and 3000 or less in a total glycol monomer (B) unit of 0.5 mol% or more and 15 mol% It is preferable to use a polyester-based resin composed of structural units containing:

  The aromatic dicarboxylic acid imparts heat resistance and mechanical strength to the obtained polyester resin, and is 80 mol% or more, preferably 85 mol% or more, in all carboxylic acid monomer (A) units. Preferably 90 mol% or more is contained. When the aromatic dicarboxylic acid accounts for 80 mol% or more in the total dicarboxylic acid monomer (a), the resulting polyester-based resin exhibits good heat resistance and mechanical strength. On the other hand, the upper limit of the aromatic dicarboxylic acid is not particularly limited and is preferably 100 mol% or less.

  The type of aromatic dicarboxylic acid is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, naphthalene-1,4 or 2,6-dicarboxylic acid, anthracene dicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4 ′. -Diphenyl ether dicarboxylic acid, 5-sulfoisophthalic acid, sodium 3-sulfoisophthalate, etc. can be mentioned. Aromatic dicarboxylic acids may be subjected to polymerization as their esters. There is no restriction | limiting in particular in aromatic dicarboxylic acid ester, The said ester of aromatic dicarboxylic acid is preferable, and a lower alkyl ester, aryl ester, carbonate ester, an acid halide, etc. can be used. Further, the carboxylic acid monomer (A) unit may contain a small amount of an aliphatic dicarboxylic acid (usually in a range of less than 20 mol%). The aliphatic dicarboxylic acid is not particularly limited, and oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3- or 1,4-cyclohexanedicarboxylic acid An acid, cyclopentane dicarboxylic acid, 4,4'-dicyclohexyl dicarboxylic acid, etc. are mentioned.

  The glycol monomer (B) unit in the polyester resin used in the present invention is 1,4-cyclohexanedimethanol (hereinafter also simply referred to as “1,4-CHDM”) 0.1 mol% or more and 40 mol. % Or less. 1,4-CHDM used for the glycol monomer (b) mainly has a role of imparting impact resistance to the obtained polyester resin.

  Conventionally, when a polyester resin composed of terephthalic acid, ethylene glycol and 1,4-CHDM, and a polycarbonate resin are mixed to obtain a mixed resin composition, the polyester resin and the polycarbonate resin are well balanced. In order to obtain a resin composition having both a single transparent Tg and good mechanical properties, it is common to contain at least 40 mol% of 1,4-CHDM (for example, Res). .Discl. (UK), 229, 182 (1983)). However, polyester resins containing 1,4-CHDM in an amount of 40 mol% or more usually have a Tg of about 80 ° C. or more. Therefore, the Tg of a mixed resin composition with a polycarbonate resin is less than that of a PVC resin. It was difficult to control the temperature range for the next processing (usually about 50 ° C. or more and 100 ° C. or less). As a result of intensive studies, the present inventors have determined that if the mixed resin composition is a polycarbonate resin and a specific polyester resin, the content of 1,4-CHDM in the polyester resin is 40 mol% or less. Even so, it was found that they have compatibility.

  If the content of 1,4-CHDM in all glycol monomers (b) is 0.1 mol% or more, impact resistance can be imparted to the resulting polyester resin, and the upper limit is 40. If it is less than mol%, the effect of lowering the Tg of the resulting polyester resin can be obtained. Preferably, the content of 1,4-CHDM in all glycol monomers (b) is 1 mol% or more and 35 mol% or less. 1,4-CHDM has two types of isomers, a cis type and a trans type.

  In the present invention, the polyalkylene glycol used in the glycol monomer (b) has a number average molecular weight of 500 or more and 3000 or less, and its content is 0.5 mol% or more and 15 mol% or less. This polyalkylene glycol mainly imparts flexibility and low Tg (0 to 50 ° C.) to the obtained polyester resin. By setting the number average molecular weight of the polyalkylene glycol to 500 or more, sufficient flexibility can be imparted to the resulting polyester resin, and by setting the upper limit to 3000 or less, compatibility with other components and polymers can be achieved. The polymerization reaction does not stagnate, and an appropriate mechanical strength can be imparted to the resulting polyester resin. The number average molecular weight of the polyalkylene glycol is preferably 800 or more, more preferably 1000 or more, and the upper limit is 2000 or less, more preferably 1500 or less.

  In addition, the polyalkylene glycol may be used in combination of plural kinds having different number average molecular weights. When a plurality of types are used in combination, the number average molecular weight in a uniformly mixed state is preferably within the above range. The number average molecular weight of the polyalkylene glycol can be measured by a general method such as gel permeation chromatography.

  Further, since the polyalkylene glycol is contained in the total glycol monomer (b) in an amount of 0.5 mol% or more, the resulting polyester resin can be provided with sufficient flexibility and low Tg, and the upper limit is 15 mol. % Or less, it is possible to suppress a decrease in thermal stability and mechanical strength of the obtained polyester resin. For this reason, the polyalkylene glycol is 1 mol% or more, preferably 2 mol% or more in the total glycol monomer (b), and the upper limit is 10 mol% or less, preferably 8 mol% or less. Desirably included.

Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block copolymer, polytetramethylene glycol, polyhexamethylene glycol and the like. Among them, polytetramethylene glycol is preferably used. These can be used individually by 1 type or in mixture of 2 or more types.

  There are no particular restrictions on the other glycol components used in the glycol monomer (b) other than the components described above, and ethylene glycol, diethylene glycol (including by-product components), 1,2-propylene glycol, 1, 3-propanediol, 2,2-dimethyl-1,3-propanediol, trans- or cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl Glycol, 1,5-pentanediol, 1,6-hexanediol, 1,3-cyclohexanedimethanol, decamethylene glycol, cyclohexanediol, p-xylenediol, bisphenol A, tetrabromobisphenol A, tetrabromobisphenol A-bis (2-hydroxyethyl ether) It is. These can be used singly or in combination of two or more, and can impart color tone, transparency, heat resistance, impact resistance, etc. to the polyester resin as appropriate. Molding of the resulting polyester resin Ethylene glycol is preferably used because it can provide thermal stability at the time and is inexpensive and easily available industrially.

  For the purpose of adjusting flexibility, melt viscosity, transparency, mechanical properties, solvent resistance, etc., the polyester resin used in the present invention is a trivalent or higher polyvalent carboxylic acid compound and / or other than the above-described components. A smaller amount of a trihydric or higher polyhydric alcohol component (usually about 0.05 mol% to 2 mol%) may be copolymerized.

  Examples of the polyvalent carboxylic acid compound include trimellitic acid, pyromellitic acid, and anhydrides thereof. Examples of the polyhydric alcohol include trimethylolpropane, pentaerythritol, and glycerin. . These can be used individually by 1 type or in mixture of 2 or more types. However, when the polyvalent carboxylic acid compound or the polyhydric alcohol is used alone, the content of the polyvalent carboxylic acid compound or the polyhydric alcohol is usually 0 in the carboxylic acid monomer (i), respectively. 0.05 mol% or more, preferably 0.1 mol% or more, and the upper limit is 2 mol% or less, preferably 1 mol% or less. Moreover, when using together the said polyhydric carboxylic acid compound and a polyhydric alcohol, content in the said carboxylic acid monomer (ii) of the said polyhydric carboxylic acid compound, and the said glycol monomer of the said polyhydric alcohol The total content in (b) is usually 0.05 mol% or more, preferably 0.1 mol% or more, and the upper limit is 2 mol% or less, preferably 1 mol% or less. If the content of these polycarboxylic acid compounds and / or polyhydric alcohols is 0.05 mol% or more in each of the above cases, the resulting polyester resin has a sufficient improvement effect in flexibility and melt viscosity. It can be expected, and if it is 2 mol% or less, it does not become difficult to control the reaction due to gelation, and the occurrence of fish eyes can be suppressed in the resulting heat-shrinkable film, which is preferable.

  The polyester resin used in the present invention can be produced by a known direct polymerization method, transesterification method, etc., and if necessary, an esterification catalyst such as titanium butoxide, dibutyltin oxide, magnesium acetate, manganese acetate, transesterification A catalyst or a polymerization catalyst such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide and the like can be used.

The intrinsic viscosity of the polyester resin measured at 30 ° C. using tetrachloroethane / phenol (mass ratio 1/1) as a solvent is 0.4 dl / g or more, preferably 0.7 dl / g or more, and 1.5 dl / G or less, preferably 1.2 dl / g or less. Here, if the intrinsic viscosity is 0.4 dl / g or more, the moisture resistance and mechanical strength of the resulting polyester-based resin do not decrease, and if the upper limit is 1.5 dl / g or less, the polymerization takes a long time. Is preferable from the viewpoint of production cycle and cost.
In the present invention, one type of polyester resin may be used alone, or two or more types may be mixed and used.

  In the present invention, when an aromatic polycarbonate resin is used, the mixing amount of the aromatic polycarbonate resin and the polyester resin is such that the aromatic polycarbonate resin is 30% by mass to 70% by mass, and the polyester resin Is 30 mass% or more and 70 mass% or less. When the upper limit of the content of the aromatic polycarbonate resin is 70% by mass or less and the lower limit of the content of the polyester resin is 30% by mass or more, the Tg of the mixed resin composition is adjusted to a desired range. In addition, since good stretchability can be obtained, the heat shrinkability defined in the present invention can be imparted. Moreover, if the lower limit of the aromatic polycarbonate resin is 30% by mass or more and the upper limit of the polyester resin is 70% by mass or less, the Tg of the mixed resin composition does not become too low, and good natural shrinkage is achieved. Rate is obtained, and an appropriate film waist is obtained, which is preferable. In the present invention, the mixing amount of the aromatic polycarbonate resin and the polyester resin is such that the aromatic polycarbonate resin is 65% by mass or more and 40% by mass or less, and the polyester resin is 35% by mass or more and 60% by mass or less. It is preferable that

  Next, the mixed resin composition comprising the aromatic polycarbonate resin used in the present invention and the polyester resin has a single Tg measured at a heating rate of 10 ° C./min by differential scanning calorimetry, Tg is preferably between the Tg of the aromatic polycarbonate resin and the Tg of the polyester resin, and the Tg is preferably 50 ° C. or higher and 100 ° C. or lower. Here, the Tg of the mixed resin composition is single when the Tg of the mixed resin composition is measured using a differential scanning calorimeter at a heating rate of 10 ° C./min according to JIS K7121. , Meaning that only one peak indicating Tg appears. When the mixed resin composition has a single Tg and the Tg is between the Tg of the aromatic polycarbonate resin and the Tg of the polyester resin, the aromatic polycarbonate resin and the polyester resin It becomes possible to obtain a heat-shrinkable film having good compatibility and excellent transparency.

  The Tg measured at a heating rate of 10 ° C./min by differential scanning calorimetry of the mixed resin composition used in the present invention is preferably 50 ° C. or more and 100 ° C. or less. If the Tg of the mixed resin composition is 50 ° C. or more, it is practically preferable because natural shrinkage of the resulting heat-shrinkable film is reduced and excellent dimensional stability is obtained. On the other hand, if the Tg of the mixed resin composition is 100 ° C. or lower, shrinkage requiring a relatively short time (several seconds to several tens of seconds) and a high shrinkage finish for PET bottle labeling and the like are required. This is preferable because shrinkage characteristics such as shrinkage rate, shrinkage start temperature, shrinkage gradient, and the like, which are adaptable to processing steps, can be imparted. More preferably, the Tg of the mixed resin composition is 55 ° C. or higher and 95 ° C. or lower, and more preferably 60 ° C. or higher and 85 ° C. or lower.

  The Tg measured by differential scanning calorimetry of the aromatic polycarbonate resin is usually about 150 ° C., so that the aromatic polycarbonate resin is 30% by mass to 70% by mass and the polyester resin is 30% by mass to 70% by mass. In order to make Tg into the range of 50 degreeC or more and 100 degrees C or less with the following mixed resin compositions, it is preferable that Tg of a polyester-type resin is the range of 0 degreeC or more and 50 degrees C or less. Here, if the Tg of the polyester resin is 0 ° C. or higher, the occurrence of blocking can be suppressed, the handling of the raw material pellets becomes easy, and if the upper limit is 50 ° C. or lower, the Tg of the mixed resin composition is lowered. This is preferable because the effect of the above is obtained. More preferably, the Tg of the polyester resin is 5 ° C. or higher and 45 ° C. or lower, and more preferably 5 ° C. or higher and 40 ° C. or lower.

  In the mixed resin composition used in the present invention, a polyester other than the polyester-based resin is used for the purpose of improving and adjusting various physical properties of the moldability and heat-shrinkable film within a range that does not significantly impair the effects of the present invention. Resin such as polyether, polyamide, polyolefin, polymethyl methacrylate, rubber-like modifiers such as core-shell, graft or linear random and block copolymers, silica, talc, kaolin, calcium carbonate, etc. Inorganic particles, pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, hydrolysis inhibitors (carbodiimide compound monomers or polymers, etc.), antistatic agents, melt viscosity improvers In addition, additives such as a crosslinking agent, a lubricant, a nucleating agent, a plasticizer, and an anti-aging agent may be added as appropriate.

  Next, the heat shrinkable film of the present invention needs to have a heat shrinkage rate of 20% or more in at least one direction when immersed in 80 ° C. warm water for 10 seconds. This is an index for determining the adaptability to the shrinking process in a relatively short time (several seconds to about several tens of seconds) such as the use of shrinkage labels for PET bottles. For example, the required shrinkage rate required for a heat-shrinkable film applied to shrinkage labels for PET bottles varies depending on the shape, but is generally about 20 to 40%. Further, the heat-shrinkable film needs to sufficiently heat-shrink at a temperature as low as possible from the viewpoint of the influence of heat on the object to be coated. In addition, the shrinkage processing machine that is most commonly used industrially for label mounting applications of PET bottles is generally called a steam shrinker that uses steam at a predetermined temperature as a heating medium for shrinkage processing. . Considering these circumstances, a film having a heat shrinkage rate of 20% or more under the above conditions can be sufficiently adhered to the coating target within the shrinkage processing time, which is preferable from the viewpoint of productivity. In the present invention, the heat shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is at least 30%, preferably 40% or more, and the upper limit is 80% or less, preferably in the main shrinkage direction. It is desirable that it is 65% or less.

  Moreover, in the shrinkage label use of a PET bottle, it is preferable that the heat shrinkage rate when immersed for 10 seconds in 80 ° C. warm water in a direction orthogonal to the main shrinkage direction is 10% or less, and more preferably 7% or less. preferable. Here, if the film has a heat shrinkage rate of 10% or less in the direction orthogonal to the main shrinkage direction, the dimension itself in the direction orthogonal to the main shrinkage direction after shrinkage is shortened, or the printed pattern or character after shrinkage is shortened. There is no distortion or the like, and in the case of a square bottle, it is preferable because troubles such as vertical sink can be suppressed.

  The heat-shrinkable film of the present invention has a heat shrinkage rate in the main film shrinkage direction when immersed in warm water at 70 ° C. for 10 seconds and a heat shrinkage rate in the film main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds. The difference is 40% or less, preferably 35% or less, more preferably 30% or less. By setting the difference in heat shrinkage between 70 ° C. and 80 ° C. to 40% or less, the shrinkage unevenness due to the temperature unevenness of the steam is suppressed when the bottle is attached with the steam shrinker. As a result, wrinkles, avatars, etc. The formation of can be suppressed.

  Although it is desirable that the natural shrinkage rate of the heat-shrinkable film of the present invention is as small as possible, generally the natural shrinkage rate of the heat-shrinkable film is, for example, 2.0% or less after 30 days of storage at 30 ° C. Preferably, it is 1.0% or less, more preferably 0.8% or less. If the natural shrinkage rate under the above conditions is 2.0%, even if the produced film is stored for a long period of time, it can be stably attached to a container or the like, and it is difficult to cause problems in practice.

  Next, although the manufacturing method of the heat-shrinkable film of this invention is demonstrated, it can carry out by a conventionally well-known method and is not specifically limited. For example, a heat-shrinkable film can be produced by melt-extruding a mixed resin composition comprising the polycarbonate resin and the polyester resin with an extruder. Alternatively, the resin composition as a raw material can be previously melt-kneaded and cut into pellets, and then the pellet-shaped resin composition is melt-extruded again to produce a heat-shrinkable film. For extrusion, any existing method such as a T-die method or a tuber method may be employed.

  For melt kneading, commonly used single screw extruders, twin screw extruders, kneaders, mixers, etc. can be used, although not particularly limited, uniform dispersibility of the mixed resin composition, heat obtained It is preferable to use a twin screw extruder because of the stability of the mechanical strength of the shrinkable film and the transparency. Moreover, in this invention, it is preferable to suppress as much as possible the reaction (transesterification reaction etc.) which generate | occur | produces between polycarbonate-type resin and polyester-type resin at the time of melt-kneading. If the reaction proceeds excessively, not only the thermal properties of the resulting mixed resin composition are deteriorated, but also a foaming phenomenon may appear in the melt-extruded sheet due to coloring or gas generation, which is not preferable. For this reason, the type of raw material catalyst used (Ge-based catalyst is preferably used) and the amount of catalyst remaining in the raw material, or the temperature and residence time during melt-kneading, if necessary, a phosphorus compound It is preferable to pay attention to addition of a transesterification inhibitor such as phosphoric acid or phosphorous acid compound. For example, the molding temperature in the T-die method is appropriately adjusted depending on the flow characteristics and film forming properties of the mixed resin composition, but is generally about 320 ° C. or lower, preferably 240 ° C. or higher and 280 ° C. or lower. The melt-extruded resin is cooled by a cooling roll, air, water, etc., and then reheated by an appropriate method such as hot air, hot water, infrared rays, microwaves, etc., and 1 1 by a roll method, a tenter method, a tubular method, etc. Stretched in the axial or biaxial direction.

  The stretching temperature needs to be changed depending on the Tg of the resin composition to be used and the properties required for the heat-shrinkable film, but is generally 60 ° C. or higher, preferably 70 ° C., and 130 ° C. or lower, preferably 120 ° C. or lower. Controlled by range. The draw ratio is 1.5 times or more and 10 times or less, preferably 1.7 times or more and 7 times in the main shrinkage direction depending on the characteristics of the resin composition used, the stretching means, the stretching temperature, the target product form, and the like. It is appropriately determined in the direction of one axis or two axes within a range of less than double. Even in the case of uniaxial stretching in the transverse direction, it is also effective to impart weak stretching of about 1.05 to 1.8 times in the longitudinal direction for the purpose of improving the mechanical properties of the film. Next, the stretched film is subjected to a heat treatment or relaxation treatment at a temperature of about 50 ° C. or more and 100 ° C. or less for the purpose of reducing the natural shrinkage rate or improving the heat shrink property, if necessary. It cools rapidly within the time not to relax, and becomes a heat-shrinkable film.

  The thickness of the heat-shrinkable film of the present invention is not particularly limited, but usually the lower limit is 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and the upper limit is 100 μm or less, preferably 80 μm or less. More preferably, the thickness is 60 μm or less. Here, if the lower limit of the thickness of the heat-shrinkable film is 5 μm or more, the handleability of the film is easy, and if the upper limit is 100 μm or less, the shrinkability is excellent and economically preferable. In addition, the heat-shrinkable film of the present invention may be subjected to surface treatment and surface treatment such as corona treatment, printing, coating, and vapor deposition, as well as bag making and perforation treatment with various solvents and heat sealing, as necessary. Can be applied.

  In the heat-shrinkable film of the present invention, it is important that the tensile elastic modulus in the direction orthogonal to the main shrinkage direction of the film is 1200 MPa or more, more preferably 1800 MPa, from the viewpoint of waist strength (rigidity at normal temperature). More preferably, it is 2000 MPa or more. Moreover, the upper limit of the tensile elasticity modulus of the heat shrinkable film used normally is about 4000 MPa, Preferably it is about 3000 MPa. If the tensile modulus of elasticity in the direction perpendicular to the main shrinkage direction of the film is 1500 MPa or more, the waist as a whole film (rigidity at room temperature) can be increased. Even when the thickness of the film is reduced, the PET bottle When a film made in a container is covered with a labeling machine or the like, it is difficult to cause problems such as being obliquely covered or being liable to decrease the yield due to film folding or the like. The said tensile elasticity modulus can be measured on 23 degreeC conditions according to JISK7127.

  Further, the tensile elastic modulus in the main shrinkage direction of the film is not particularly limited as long as the elasticity of the film is obtained, but it is 1200 MPa or more, preferably 1800 MPa or more, more preferably 2000 MPa or more, and the upper limit is about 6000 MPa, preferably 4500 MPa. About, more preferably, about 4000 MPa. By setting the tensile elastic modulus in the main shrinkage direction of the film within the above range, it is preferable because the strength of the film can be enhanced in both directions.

  For example, when the film having a thickness of 50 μm is measured according to JIS K7105, the haze value is preferably 10% or less, and more preferably 7% or less. More preferably, it is 5% or less. If the haze value is 10% or less, the transparency of the film can be obtained and a display effect can be achieved.

  The rupture resistance of the film of the present invention is evaluated by the tensile rupture elongation, and in a tensile rupture test under an environment of 0 ° C., particularly in a label application, the elongation is 100% or more in the film take-off (flow) direction (MD), Preferably it is 200% or more, More preferably, it is 300% or more. If the tensile elongation at break in an environment of 0 ° C. is 100% or more, it is difficult to cause problems such as breakage of the film at the time of printing / bag making and the like, which is preferable. In addition, even when the tension applied to the film increases as the speed of processes such as printing and bag making increases, it is more preferable that the tensile elongation at break is 200% or more, which makes it difficult to break.

  The sealing strength of the film of the present invention is 3 N / 15 mm width or more, preferably 5 N / mm or more by using a method of peeling at a test speed of 200 mm / min in the main shrinkage direction by a T-type peeling method in an environment of 23 ° C. and 50% RH. It is 15 mm width or more, more preferably 7 N / 15 mm width or more. The upper limit of the seal strength is not particularly limited, but is preferably about 15 N / 15 mm width from the viewpoint of solvent resistance on the film surface.

[Shrink label and package]
The heat-shrinkable film of the present invention has excellent shrinkage finish, natural shrinkage, transparency, film stiffness (rigidity at room temperature), mechanical strength such as fracture resistance, etc. Although it is not limited, it can be used for shrinkage labels for PET bottles (round and square bottles of about 300 milliliters to 2 liters), shrinkage packaging for various foods and articles, shrinkage wrapping packaging, cap seals for various containers, It can be suitably used as a shrinkage label for shrinkage tubes of various foods and articles, and a package equipped with this shrinkage label can be obtained. And the shrinkage | contraction label and package of this invention can be produced using a normal method.

  Since the heat-shrinkable film of the present invention has excellent shrinkage finishing properties and shrinkage properties, in addition to the heat-shrinkable label material of a plastic molded product that deforms when heated to a high temperature, it has a coefficient of thermal expansion, water absorption, etc. Materials very different from the heat-shrinkable film of the present invention, for example, polyolefin resin such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene, polymethacrylate resin, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate It can utilize suitably as a heat-shrinkable label raw material of the package (container) which used at least 1 sort (s) chosen from polyester-type resins, such as such as a constituent material.

  Examples of the material constituting the plastic package in which the heat-shrinkable film of the present invention can be used include polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer in addition to the above resins. Polymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), methacrylate ester-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenol resin, urea resin, A melamine resin, an epoxy resin, an unsaturated polyester resin, a silicone resin, etc. can be mentioned. These plastic packages may be a mixture of two or more resins or a laminate.

  The contents of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited by these. In addition, the various measured values and evaluation about the film displayed in this specification were performed as follows. Here, the flow direction from the extruder of a film is called the vertical direction (MD), and the orthogonal direction is called a horizontal direction (TD).

(1) Glass transition temperature (Tg)
Using DSC-7 manufactured by PerkinElmer Co., Ltd., 10 mg of a sample cut from the cast sheet was heated from −40 ° C. to 250 ° C. at a heating rate of 10 ° C./min according to JIS K7121, and 1 at 250 ° C. The temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min after holding for 1 minute, held at −40 ° C. for 1 minute, and then re-heated at a heating rate of 10 ° C./min. )

(2) Dynamic Viscoelasticity Measurement A sample 4 mm long and 60 mm wide was cut out from the obtained heat-shrinkable film, and using a viscoelastic spectrometer DVA-200 (manufactured by IT Measurement Co., Ltd.), vibration frequency 10 Hz, strain 0 .Initial temperature rise from -50 ° C in the transverse direction under conditions of 1%, temperature rise rate 3 ° C / min, 25 mm between chucks, and measured storage elastic modulus (E ') and loss elastic modulus (E ") From the obtained data, the number of peaks of the loss tangent (tan δ = E ″ / E ′) curve, the peak temperature, its half width, and the peak value were determined.

(3) a solution obtained by dissolving composition analysis polyester resin polyester resin deuterochloroform (solvent): a (sample concentration 100 mg / 1 milliliters solvent) sample by the solution sample nuclear magnetic resonance (NMR) ¹ Analysis was performed by monitoring H, and the mol% with respect to all carboxylic acid monomer units was determined for carboxylic acid monomer units, and the mol% with respect to all glycol monomer units was determined for glycol monomer units.

(4) Average refractive index According to JIS K7142, it measured using the Abago refractometer made from an Atago Co., Ltd. by using sodium D line | wire (589 nm) as a light source.

(5) Haze value (cloudiness value)
The haze value of the film was measured at a film thickness of 50 μm according to JIS K7105.

(6) Tensile modulus According to JIS K7127, the sample was measured in the transverse direction under the conditions of a temperature of 23 ° C. and a test speed of 5 mm / min.

(7) Tensile Fracture Strength, Tensile Fracture Elongation According to JIS K7127, the transverse direction of the sample was measured at a temperature of 23 ° C. and a test speed of 200 mm / min.

(8) Natural shrinkage rate A sample having a size of 1000 mm in the vertical direction and 1000 mm in the horizontal direction is cut out from the obtained heat-shrinkable film, and left in a thermostatic bath at 30 ° C. for 30 days to determine the main shrinkage direction (lateral direction). The amount of shrinkage relative to the original size before shrinkage was measured, and the ratio was determined as a% value.

(9) Heat Shrinkage A sample having a size of 100 mm in the vertical direction and 100 mm in the horizontal direction was cut from the obtained heat-shrinkable film and immersed in a hot water bath at 80 ° C. for 10 seconds to measure the amount of shrinkage in the vertical and horizontal directions. Then, the ratio of the shrinkage amount to the original size before shrinkage was obtained as a% value. In addition, the minus (-) of the ratio means that it has expanded more than the original size.

(10) Shrinkage finishing property A film printed with a grid of 10 mm in length and width was cut into a size of 100 mm in the vertical direction and 298 mm in the horizontal direction, 10 mm on both ends in the horizontal direction, and bonded with a solvent or the like to form a cylinder. This cylindrical film was attached to a 1.5-liter round PET bottle with an internal capacity of 10 seconds without rotating through a steam heating type 3 m-length shrink tunnel. The blowing steam temperature was 99 ° C., and the tunnel atmosphere temperature was 90 to 94 ° C. After coating the film, the shrinkage finish was evaluated according to the following criteria.
(◯): Shrinkage is sufficient, wrinkled, no avatar, lattice distortion is practically satisfactory, and film adhesion is good (×): There is a clearly insufficient shrinkage part, or Wrinkled, avatar, lattice distortion is conspicuous

(Example 1)
As shown in Table 1, as a polycarbonate resin, a dried aromatic polycarbonate resin (manufactured by Mitsubishi Engineering Plastics Co., Ltd., Novalex 7025A, Tg: 149.5 ° C., average refractive index: 1.5858) (hereinafter simply referred to as “polycarbonate resin”) PC mass (which may be abbreviated to PC) 50% by weight, and as a polyester resin, a dried transparent soft polyester resin (Mitsubishi Rayon Co., Ltd., Dianite DN-124, Tg: 19.1 ° C., carboxylic acid monomer (A) Unit: 100 mol% terephthalic acid, glycol monomer (b) Unit: 66 mol% ethylene glycol, 2 mol% diethylene glycol, 26 mol% 1,4-cyclohexanedimethanol, polytetramethylene having a number average molecular weight of 1000 Glycol 6 mol%, average refractive index: 1.5461, intrinsic viscosity: 0.94 l / g) (hereinafter simply referred to as PET-1) 50% by mass using a φ40 mm co-directional twin screw extruder (L / D = 36) equipped with a T die The mixture is melt-kneaded at a set temperature of 270 ° C. and 50 ° C. (in Example 2 and later, the temperature of the cast roll is a temperature around Tg−20 ° C. of the resin composition while confirming the adhesion state of the sheet to the cast roll. A cast sheet having a thickness of 150 μm was obtained by forming a film with a cast roll appropriately adjusted). Subsequently, the obtained sheet was stretched 3.0 times in the transverse direction at a stretching temperature of 95 ° C. using a tenter stretching facility, and then quenched with cold air to obtain a heat-shrinkable film having a thickness of 50 μm. Table 2 shows the evaluation results such as Tg evaluated using the obtained cast sheet and the mechanical properties evaluated using the obtained heat-shrinkable film. Moreover, the loss tangent curve in the obtained heat-shrinkable film is shown in FIG.

(Example 2)
As shown in Table 1, the mixing ratio of PC-1 used as polycarbonate resin and PET-1 used as polyester resin in Example 1 was changed to 60% by mass and 40% by mass, respectively, and the stretching temperature was set to 105 ° C. A heat-shrinkable film was obtained in the same manner as in Example 1 except for the change. Table 2 shows the evaluation results such as Tg evaluated using the obtained cast sheet and the mechanical properties evaluated using the obtained heat-shrinkable film. Moreover, the loss tangent curve in the obtained heat-shrinkable film is shown in FIG.

(Comparative Example 1)
As shown in Table 1, the mixing ratio of PC-1 used as the polycarbonate resin and PET-1 used as the polyester resin in Example 1 was changed to 80% by mass and 20% by mass, respectively, and the stretching temperature was set to 135 ° C. A heat-shrinkable film was obtained in the same manner as in Example 1 except for the change. Table 2 shows the evaluation results such as Tg evaluated using the obtained cast sheet and the mechanical properties evaluated using the obtained heat-shrinkable film. Moreover, the loss tangent curve in the obtained heat-shrinkable film is shown in FIG.

(Comparative Example 2)
As shown in Table 1, in place of PET-1 used as the polyester-based resin in Example 1, amorphous polyester resin [Eastman Chemical Co., Ltd., EASTAR PETG Polyester 6663, Tg: 79.0 ° C., carvone Acid monomer (a) unit: terephthalic acid 100 mol%, glycol monomer (b) unit: ethylene glycol 68 mol%, 1,4-cyclohexanedimethanol 32 mol%, average refractive index: 1.5667] ( Hereinafter, a sheet was obtained in the same manner as in Example 1 except that (which may be simply abbreviated as PET-2) was used. Subsequently, an attempt was made to stretch the obtained sheet 3.0 times in the transverse direction at a stretching temperature of 95 ° C. using a tenter-stretching facility, but the film was not stretchable due to film breakage. Moreover, the obtained sheet showed Tg at two locations of 79.4 ° C. and 134.8 ° C. (see Table 2).

(Comparative Example 3)
As shown in Table 1, a heat-shrinkable film was obtained in the same manner as in Example 1 except that the PET-2 alone used in Comparative Example 2 was changed and the stretching temperature was changed to 90 ° C. Table 2 shows the evaluation results such as Tg evaluated using the obtained cast sheet and the mechanical properties evaluated using the obtained heat-shrinkable film. Moreover, the loss tangent curve in the obtained heat-shrinkable film is shown in FIG.

  From Tables 1 and 2, the heat shrinkable film obtained by stretching the mixed resin composition of the polycarbonate resin and the polyester resin specified in the present invention has both the peak temperature and the half width of tan δ within the scope of the present invention. It is understood that the balance of mechanical strength such as shrink finish, natural shrinkage, transparency, film stiffness (rigidity at room temperature), and fracture resistance is excellent (Examples 1 and 2). On the other hand, in the mixed resin composition, when the blending ratio of the polycarbonate resin is large, Tg increases and the tan δ peak temperature is outside the range defined by the present invention. It was difficult to impart properties (Comparative Example 1). Moreover, when using polyester-type resin outside the range prescribed | regulated by this invention, it turns out that it is inferior to compatibility with polycarbonate-type resin, and it is difficult to obtain a heat-shrinkable film (comparative example 2). Furthermore, it can be seen that the heat-shrinkable film obtained by stretching a single polyester-based resin has a narrow tan δ half-width, which falls outside the scope of the present invention, and is inferior in shrink finish (Comparative 3).

It is a figure which shows the loss tangent (tan-delta) curve of Examples 1 and 2 of this invention, and Comparative Examples 1 and 3. FIG.

Claims (8)

  Heat when a mixed resin composition comprising a polycarbonate resin and a polyester resin that shifts the glass transition temperature derived from the polycarbonate resin to a low temperature side is stretched in at least one direction and immersed in warm water at 80 ° C. for 10 seconds. A heat shrinkable film having a shrinkage rate of 20% or more in at least one direction, and a peak of a loss tangent (tan δ) curve measured at a vibration frequency of 10 Hz by dynamic viscoelasticity measurement is 70 ° C. or higher and 130 ° C. or lower. A heat-shrinkable film characterized by being present as a single peak in a range and having a half width of 15 ° C. or more of the loss tangent curve.   The heat-shrinkable film according to claim 1, wherein the polycarbonate resin is an aromatic polycarbonate resin.   A film obtained by stretching a mixed resin composition comprising 30% by mass or more and 70% by mass or less of an aromatic polycarbonate resin and 30% by mass or more and 70% by mass or less of a polyester resin in at least one direction, As the carboxylic acid monomer (a) unit, the total carboxylic acid monomer (a) unit contains 80 to 100 mol% of aromatic dicarboxylic acid, and as a glycol monomer (b) unit. 1,4-cyclohexanedimethanol 0.1 mol% or more and 40 mol% or less and polyalkylene glycol having a number average molecular weight of 500 or more and 3000 or less and 0.5 mol% or more and 15 mol% in all glycol monomer (b) units It consists of structural units containing the following, and the thermal shrinkage rate when immersed in warm water at 80 ° C. for 10 seconds is 20% in at least one direction: Heat-shrinkable film, which is a top.   The glass transition temperature of the mixed resin composition measured by differential scanning calorimetry at a heating rate of 10 ° C./min shows a single value, and the glass transition temperature is a glass transition temperature of an aromatic polycarbonate resin and a glass of a polyester resin. The heat-shrinkable film according to claim 2 or 3, which is between the transition temperature.   The heat-shrinkable film according to any one of claims 1 to 4, wherein the mixed resin composition has a glass transition temperature of 50 ° C or higher and 100 ° C or lower.   The heat-shrinkable film according to any one of claims 1 to 5, wherein the polyester resin has a glass transition temperature of 0 ° C or higher and 50 ° C or lower.   A shrinkable label using the heat-shrinkable film according to claim 1.   A package equipped with the shrinkable label according to claim 7.

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