JP2008285621A - Light-shielding heat-shrinkable film, molded product and heat-shrinkable label using the light-shielding heat-shrinkable film and container using the molded product or onto which the label is fitted - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-shielding heat-shrinkable film which reduces environmental burden and is excellent in light-shielding property, high rigidity, breakage resistance, shrinkage property, film appearance and film-forming property, a molded product and a heat-shrinkable label using the light-shielding heat-shrinkable film, and a container using the molded product or onto which the label is fitted. <P>SOLUTION: The light-shielding heat-shrinkable film comprises a polyester resin (A), a thermoplastic resin (B) immiscible with the polyester resin (A), a compatibilizer (C) and a filler (D), provided that the mass ratio of the resin (A) to the resin (B) is from 99/1 to 1/99, the content of the compatibilizer (C) is 3-20 mass%, and the content of the filler (D) is ≤40 pts.mass. After the film is stretched at least uniaxially and soaked in hot water of 80°C for 10 sec, the shrinking rate in the main shrinkage direction is ≥20%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-shielding heat-shrinkable film, a molded product using the light-shielding heat-shrinkable film, a heat-shrinkable label, and a container using or mounting the molded product. More specifically, the present invention relates to a light-shielding shrinkable film that reduces environmental burden, has excellent light shielding properties, high rigidity, rupture resistance, shrinkage characteristics, film appearance, and excellent film forming properties, and the light shielding heat. The present invention relates to a molded article using a shrink film, a heat-shrink label, and a container using or equipped with this molded article.

  Conventionally, heat-shrinkable films have been used for packaging and bundling applications such as containers, but in recent years, many heat-shrinkable labels have a light-shielding function in order to protect the contents of containers from ultraviolet rays and visible light. It has come to be used. Along with this, after adding an aromatic polyester-based shrinkable label (see Patent Documents 1 and 2) imparted with light shielding properties and a resin incompatible with the polyester-based resin (hereinafter referred to as “incompatible resin”), the film is stretched. A heat-shrinkable film that forms holes and imparts a light-shielding function has also been developed (see Patent Document 3).

  However, a heat-shrinkable film that imparts a light-shielding function by forming pores by adding an incompatible resin and then forming pores has a problem that poor dispersion of the incompatible resin is likely to occur. As a result, it is difficult to form uniform pores, the light-shielding property is uneven throughout the film, the thickness is not constant, the film appearance is unfavorable, and the film is prone to breakage during stretching. There was also a problem with the film surface.

  On the other hand, all of the above heat-shrinkable films are often made from raw materials that use petroleum resources, and there is a problem of depletion of petroleum resources and the generation of harmful gases during combustion after use for continuous use. Because the calorie burned is too high, the combustion furnace is damaged, and the life of the furnace is shortened.

  In response to the above problems, it has been proposed to use polylactic acid that is derived from plants and that can be industrially produced as an alternative resin for polyester resins. Polylactic acid is suitable for aiming for a sustainable society because it uses corn and other biomass as a raw material, and does not generate harmful gases during combustion, and its combustion calories are low, so it does not damage the combustion furnace. Less load and preferable.

  However, when polylactic acid is used as a material for heat-shrinkable labels, it has the characteristics of high rigidity, excellent low-temperature shrinkability, and low natural shrinkage, but there is a problem in fracture resistance. It was difficult to produce a simple heat shrink label.

  In order to improve the rupture resistance of this polylactic acid, a heat-shrinkable film to which a soft component compatible with polylactic acid is added has also been proposed (see Patent Document 4). Therefore, there is a problem that the rigidity is reduced and the natural shrinkage is increased. Moreover, in order to adjust the shrink finish of the polylactic acid-based heat-shrinkable film, a heat-shrinkable film in which the isomer ratio of polylactic acid is adjusted has also been proposed (see Patent Document 5). The shrinkage property was not fully satisfied.

For the purpose of solving the above problems, heat shrinkable pore films in which polylactic acid is mixed with an incompatible resin have also been proposed (see Patent Documents 6 and 7). Due to poor dispersion of the compatible resin and the formation of nonuniform pores associated therewith, there have been problems in thickness nonuniformity, poor film appearance, and film forming properties as described above.
JP 2003-236930 A JP 2004-114498 A JP 2003-321562 A JP 2003-119367 A JP 2001-011214 A JP 2006-45296 A JP 2006-117775 A

  This invention is made | formed in view of the subject mentioned above, The subject of this invention is a light-shielding heat-shrink film which has a light-shielding function, and was excellent in the uniformity of thickness, the film external appearance, and film forming property. It is to provide. Especially when plant-derived polylactic acid resin is used as the polyester resin, it is excellent in light-shielding property, high rigidity, rupture resistance, shrinkage properties, uniformity of thickness, film appearance, and film-forming property, and environmental impact Can be provided.

  Another object of the present invention is to provide a heat-shrink label, a molded product and a container using the film suitable for applications such as shrink wrap, shrink-bound wrap and shrink labels.

  As a result of earnestly examining the heat-shrinkable film using a polyester-based resin in order to solve the above-mentioned problems, the present inventor exhibited a sufficient light-shielding function, thickness uniformity, film appearance, and film forming property. The present invention was completed by successfully obtaining a heat-shrinkable film excellent in heat resistance.

That is, an object of the present invention is to provide a polyester resin (A), a thermoplastic resin (B) incompatible with the polyester resin (A), a compatibilizer (C), and a filler (D). The unstretched film contained in the relationship (1) to (3) below is stretched in at least one direction, and the shrinkage rate in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds is 20% or more. This is solved by a light-shielding heat-shrinkable film.
(1) Mass ratio of polyester resin (A) to thermoplastic resin (B) (A / B): 99/1 to 1/99
(2) Content of compatibilizing agent (C): 3% by mass or more and 20% by mass or less (3) filling with respect to the total amount of polyester resin (A), thermoplastic resin (B) and compatibilizing agent (C) Content of agent (D): 0 to 40 parts by mass with respect to 100 parts by mass of the resin constituting the film

  In the light-shielding heat-shrinkable film of the present invention, the polyester resin (A) is preferably a polylactic acid resin.

  The light-shielding heat-shrinkable film of the present invention can contain a soft component (E) other than the polyester resin (A) and the thermoplastic resin (B). In that case, the polyester resin (A) and the thermoplastic resin The content of the soft component (E) with respect to the total amount of (B), the compatibilizer (C) and the soft component (E) is 5% by mass or more and 50% by mass or less.

  In the light-shielding heat-shrinkable film of the present invention, the thermoplastic resin (B) is preferably at least one selected from the group consisting of polyolefin resins, polystyrene resins, and polycarbonate resins.

  The light-shielding heat-shrinkable film of the present invention preferably has an average light transmittance of 20% or less in the wavelength range of 230 nm or more and less than 380 nm, and an average light transmittance of 40% or less in the wavelength range of 380 nm or more and 800 nm or less. .

  In the light-shielding heat-shrinkable film of the present invention, the compatibilizing agent (C) has a polar group that has a high affinity or can react with the polyester resin (A) and is compatible with the thermoplastic resin (B). Acid-modified polyolefin resin, ethylene-vinyl acetate-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate terpolymer, ethylene-ethyl acrylate-methacrylic acid It is preferably at least one selected from the group consisting of a glycidyl terpolymer, an acid-modified styrene thermoplastic resin, a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon, or a hydrogenated resin thereof. .

  In the light-shielding heat-shrinkable film of the present invention, the soft component (E) is an aliphatic polyester other than the polyester resin (A) contained therein, an aromatic aliphatic polyester, a co-polymer of a diol, a dicarboxylic acid, and a lactic acid resin. Polymer, core-shell structure type rubber, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid methyl copolymer, and styrene It is preferably at least one selected from the group consisting of elastomers.

  In the light-shielding heat-shrinkable film of the present invention, the filler (D) is preferably at least one selected from the group consisting of calcium carbonate, barium sulfate, titanium oxide and zinc oxide.

  In the light-shielding heat-shrinkable film of the present invention, the filler (D) is titanium oxide, and the average light transmittance in the wavelength range of 230 nm or more and less than 380 nm is 2% or less, and the wavelength in the range of 380 nm or more and 800 nm or less. The average light transmittance is preferably 40% or less.

  In this invention, it can be set as the laminated film which contains at least 1 layer of said light-shielding heat-shrink film further.

  Another object of the present invention is achieved by a molded product using the light-shielding heat-shrinkable film or laminated film of the present invention, a heat-shrink label, and a container equipped with the molded product or label.

  ADVANTAGE OF THE INVENTION According to this invention, the light-shielding heat-shrinkable film which exhibits sufficient light-shielding function and is excellent in high rigidity, rupture resistance, shrinkage | contraction property, film external appearance, and film forming property can be provided. In the present invention, when a lactic acid resin is used as a main component, it is useful for promoting the use of biomass and building a sustainable recycling society.

  Furthermore, according to the present invention, it is possible to provide a molded product and a heat-shrinkable label that are suitable for applications such as shrink-wrapping, shrink-bound packaging, and shrink-label having excellent shrink finish and light shielding properties. Furthermore, according to the present invention, it can be fixed in a desired position regardless of the shape of the attached object, has no abnormalities such as wrinkles, avatars, insufficient shrinkage, etc., and has a beautiful light-shielding appearance. It is possible to provide a container equipped with the molded article or the heat-shrink label.

  Hereinafter, the light-shielding heat-shrinkable film, laminated film of the present invention (hereinafter collectively referred to as “the film of the present invention”), molded product, heat-shrinkable label, and container equipped with this molded product or heat-shrinkable label Will be described in detail.

[Light-shielding heat-shrink film]
The film of the present invention contains a polyester resin (A) as a main component.

<Polyester resin (A)>
In the film of the present invention, the polyester constituting the polyester-based resin (A) used as the main component is not particularly limited, but may be a polyester or a copolyester containing at least one dicarboxylic acid component and a diol component. preferable. Examples of the dicarboxylic acid component in this case include terephthalic acid, adipic acid, oxalic acid, malonic acid, succinic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, cyclohexane dicarboxylic acid, One or two or more known dicarboxylic acid components such as 5-sulfonate isophthalic acid and long-chain aliphatic dicarboxylic acid dodecanedioic acid, eicoic acid, dimer acid, and derivatives thereof can be exemplified. Examples of the diol component include ethylene glycol, propylene glycol, neopentyl glycol, hexamethylene glycol, 1,4-butanediol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polyalkylene glycol, 1,4- One or more known diol components such as cyclohexanedimethanol, 2-alkyl 1,3-propanediol, diethoxy compound of bisphenol A or bisphenol S can be mentioned. Moreover, as polyester-type resin (A) of this invention, not only single polyester resin but the mixed polyester resin which mixed 2 or more types of polyester resins can be used.

  The polyester resin (A) used in the film of the present invention is preferably a mixture in which at least one of a dicarboxylic acid component and a diol component is composed of two or more components. In that case, in two or more kinds of components, the main component, that is, the component with the largest amount (mol%) is used as the first component, and the component smaller than the first component is used as the component after the second component (that is, the second component). And other components, specifically, the second component, the third component,..., The nth component). By making the dicarboxylic acid component and the diol component into such a mixture system, the crystallinity of the resulting polyester-based resin can be kept low, and even when blended in the resin constituting the outer layer, This is preferable because the progress of the conversion can be suppressed.

  As a preferred diol component mixture, the ethylene glycol as the first component, and 1,4-butanediol, neopentyl glycol, diethylene glycol, polytetramethylene glycol, and 1,4-cyclohexanedimethanol as the second and subsequent components At least one selected from the group consisting of 1,4-cyclohexanedimethanol is preferred.

  As a preferable dicarboxylic acid component mixture, at least one selected from the group consisting of terephthalic acid as the first component, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, and adipic acid as the second component and the following components is included. Of these, isophthalic acid is preferred.

  The total amount of components after the second component is 10 mol% or more with respect to the total (200 mol%) of the total amount (100 mol%) of the dicarboxylic acid component and the total amount (100 mol%) of the diol component, Preferably, it is 20 mol% or more, and the upper limit is 40 mol% or less, preferably 35 mol% or less. If it is more than the said lower limit, the polyester-type resin (A) which has moderate crystallinity will be obtained, and if it is below the said upper limit, the advantage of a 1st component can be utilized. When ethylene glycol and 1,4-cyclohexanedimethanol are used, the content of 1,4-cyclohexanedimethanol is such that the total amount of ethylene glycol and 1,4-cyclohexanedimethanol is 100 mol% and the total amount of dicarboxylic acid components (100 Mol%) to a total of 200 mol%, it is 10 mol% or more and 40 mol% or less, preferably 25 mol% or more and 35 mol% or less. By using ethylene glycol and 1,4-cyclohexanedimethanol within such a content range, the resulting polyester has almost no crystallinity and breakage resistance is improved.

  As the polyester resin (A), for example, “PETG copolymer 6763” (manufactured by Eastman Chemical Co., Ltd.), “SKYGREEN PETG” (manufactured by SK Chemical Co., Ltd.) and the like are commercially available.

  However, the polyester-based resin (A) used in the present invention is a polyester resin that leads to reduction of environmental load in view of the problem of exhaustion of petroleum resources, the problem of generation of harmful gas during combustion after use, the problem of exhaustion of the furnace due to high combustion calories, etc. It is more preferable to use a lactic acid resin.

  The polylactic acid-based resin is a homopolymer of D-lactic acid or L-lactic acid, or a copolymer thereof. Specifically, poly (D-lactic acid) whose structural unit is D-lactic acid, and whose structural unit is L -Poly (L-lactic acid) which is lactic acid, and poly (DL-lactic acid) which is a copolymer of L-lactic acid and D-lactic acid, and the copolymerization ratios of D-lactic acid and L-lactic acid are different. Also included are mixtures of a plurality of the above copolymers.

  The copolymer of L-lactic acid and D-lactic acid has a copolymerization ratio of D-lactic acid and L-lactic acid (hereinafter abbreviated as “D / L ratio”) of 3/97 to 15/85, or 85 / It is preferably 15 to 97/3, more preferably 4/96 to 13/87, or more preferably 87/13 to 96/4, 5/95 to 10/90, or 90/10 to 95/5. More preferably.

  When the copolymerization ratio of D-lactic acid is higher than 97 or less than 3, it exhibits very high crystallinity, has a high melting point, and tends to be excellent in heat resistance and mechanical properties. However, when used as a heat-shrinkable film, it usually involves printing and a bag-making process using a solvent, so it is necessary to moderately reduce the crystallinity of the constituent material itself in order to improve printability and solvent sealability. It becomes. Moreover, when crystallinity is too high, orientation crystallization advances at the time of extending | stretching, and there exists a tendency for the film shrinkage | contraction characteristic at the time of heating to fall. Furthermore, even if the film has crystallization suppressed by adjusting the stretching conditions, crystallization proceeds prior to shrinkage due to heating during heat shrinkage, and as a result, there is a tendency to cause shrinkage unevenness or insufficient shrinkage. On the other hand, when the copolymerization ratio of D-lactic acid is less than 85 or higher than 15, the crystallinity is almost completely lost. As a result, when the labels collide with each other after heat shrinkage, they are fused by heat. Troubles such as end up occur easily. In addition, there is a tendency that formation of vacancies accompanying stretching is difficult to occur. Therefore, by adjusting the composition ratio of D-lactic acid and L-lactic acid in the polylactic acid resin within the above range, it is possible to obtain a heat-shrinkable film having excellent shrinkage characteristics that does not cause such problems. .

  The film of the present invention can be blended with polylactic acid resins having different D / L ratios, and blending is more preferable because the D / L ratio of the polylactic acid resins can be adjusted more easily. In this case, the average value of the D / L ratios of a plurality of lactic acid polymers may be set within the above range. By blending two or more polylactic acid resins with different D / L ratios according to the intended use, and adjusting the crystallinity, it balances heat resistance and heat shrinkage properties, and also has better pore formation. A film can be obtained.

  The polylactic acid-based resin may be a copolymer of lactic acid and α-hydroxycarboxylic acid, aliphatic diol, or aliphatic dicarboxylic acid as long as this effect is not impaired.

  Examples of the α-hydroxycarboxylic acid unit include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyn-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, Examples include bifunctional aliphatic hydroxycarboxylic acids such as 2-methylbutyric acid and 2-hydroxycaproic acid, and lactones such as caprolactone, butyrolactone, and valerolactone.

  Examples of the diol unit include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. Examples of the dicarboxylic acid unit include succinic acid, adipic acid, peric acid, sebacic acid, and dodecanedioic acid.

  The copolymerization ratio in the copolymer of lactic acid and α-hydroxycarboxylic acid is not particularly fixed, but the higher the occupancy ratio of lactic acid, the less the consumption of petroleum resources, and it is preferable. It is preferable to copolymerize at a ratio not exceeding. Specifically, the copolymerization ratio of lactic acid and α-hydroxycarboxylic acid, aliphatic diol, or aliphatic dicarboxylic acid is lactic acid: α-hydroxycarboxylic acid, aliphatic diol, or aliphatic dicarboxylic acid = 95: 5-10. : 90, preferably 90:10 to 20:80, more preferably 80:20 to 30:70. If the copolymerization ratio is within the above range, a film having a good balance of physical properties such as rigidity, transparency and impact resistance can be obtained.

  The weight (mass) average molecular weight of the polylactic acid resin is 20,000 or more, preferably 40,000 or more, and more preferably 60,000 or more. The upper limit of the weight (mass) average molecular weight is 400,000 or less, preferably 350,000 or less, and more preferably 300,000 or less. When the weight (mass) average molecular weight is 20,000 or more, an appropriate resin cohesive force can be obtained, and the film can be prevented from being insufficiently stretched or embrittled. On the other hand, if the weight (mass) average molecular weight is 400,000 or less, the melt viscosity can be lowered, which is preferable from the viewpoint of production and productivity improvement.

  As a method for producing the polylactic acid-based resin, a known method such as a condensation polymerization method or a ring-opening polymerization method can be employed. For example, in the case of a condensation polymerization method, a polylactic acid resin having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of D-lactic acid, L-lactic acid, or a mixture thereof. Further, in the ring-opening polymerization method, a lactide which is a cyclic dimer of lactic acid is subjected to ring-opening polymerization in the presence of a predetermined catalyst while using a polymerization regulator or the like, if necessary. A lactic acid resin can be obtained. The lactide includes DL-lactide, which is a dimer of L-lactic acid. By mixing and polymerizing these as necessary, a polylactic acid resin having an arbitrary composition and crystallinity can be obtained. it can. Furthermore, a small amount of chain extender such as a diisocyanate compound, diepoxy compound, acid anhydride, acid chloride, etc. may be used for the purpose of increasing the molecular weight.

  The Vicat softening point of the polylactic acid-based resin is 50 ° C. or higher, preferably 55 ° C. or higher, 95 ° C. or lower, preferably 85 ° C. or lower. If the Vicat softening point of the polylactic acid-based resin is 50 ° C. or higher, natural shrinkage can be suppressed even when the obtained light-shielding heat-shrinkable film is left at a temperature slightly higher than room temperature, for example, in summer. If the Vicat softening point of the polylactic acid-based resin is 95 ° C. or lower, low-temperature stretching can be realized during stretching of the film, and good shrinkage characteristics can be imparted to the resulting film.

  Examples of commercially available products of polylactic acid-based resins include “Nature Works” (manufactured by Nature Works LLC), “LACEA” (manufactured by Mitsui Chemicals, Inc.), and the like.

  The film of the present invention may further contain a thermoplastic resin (B) incompatible with the polylactic acid resin (A) in addition to the polylactic acid resin (A).

<Thermoplastic resin (B)>
The thermoplastic resin (B) used in the film of the present invention is not particularly limited as long as it is a thermoplastic resin incompatible with the polyester resin (A) to be used. For example, polystyrene resin, polyolefin Resin, polycarbonate resin and the like. However, regarding the thermoplastic resin (B) used, the storage elastic modulus at 80 ° C. when measured at a frequency of 10 Hz and a strain of 0.1% is the storage elastic modulus under the same conditions of the polyester resin (A) used. There is a need to exceed. In that case, a void | hole can be formed in a film by the elastic modulus difference with the polyester-type resin (A) used as a matrix in an extending process. Of these, polyolefin resins are most preferable. In this case, when the storage elastic modulus under the same conditions is 2,000 MPa or less, desired crystallinity can be obtained.

  In this specification, “incompatible” means a polyester resin when a mixed resin composition of the polyester resin (A) and the thermoplastic resin (B) is observed using an optical device such as an electron microscope. In (A) or the thermoplastic resin (B), it means a state in which the thermoplastic resin (B) or the polyester-based resin (A) has a circle-equivalent diameter and an average domain of 0.1 μm or more.

  The thermoplastic resin (B) preferably has a melt flow rate (hereinafter abbreviated as “MFR”) measured based on JIS K7211 of 0.5 g / 10 min or more, and 1.0 g / 10. More preferably, it is more than minutes. The MFR is preferably 50 g / 10 minutes or less, more preferably 35 g / 10 minutes or less, and further preferably 20 g / 10 minutes or less. When the MFR of the thermoplastic resin (B) is 1.0 g / 10 min or more, the size becomes too large when forming the dispersion domain, or the dispersion state is poor and the dispersion domains or pores are not easily generated. It is suitable without causing any troubles such as. On the other hand, if the MFR of the thermoplastic resin (B) is 50 g / 10 min or less, the size becomes too small when forming the dispersion domain, which is preferable without causing a problem.

  In the present invention, examples of polystyrene resins that can be used as the thermoplastic resin (B) include polymers of styrene monomers and copolymers of styrene monomers and other monomers copolymerizable therewith. it can. Examples of the styrene monomer include alkyl-substituted styrene such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, and 2,4-dimethylstyrene, α -1 type or more chosen from alpha-alkyl substituted styrene, such as methyl styrene and (alpha) -methyl 4-methyl styrene, halogenated styrene, such as 2-chloro styrene and 4-chloro styrene, etc. are mentioned.

  Other monomers copolymerizable with styrenic monomers include acrylic acid or methacrylic acid, methyl acrylate or methyl methacrylate, ethyl acrylate or ethyl methacrylate, butyl acrylate or butyl methacrylate, 2-ethylhexyl acrylate or N-substituted maleimide such as acrylic acid (C1-C8) ester or methacrylic acid (C1-C8) ester such as 2-ethylhexyl methacrylate, acrylonitrile, maleic anhydride, maleimide, N-methylmaleimide, N-ethylmaleimide, etc. One or more types selected from maleic acid and derivatives thereof. Of these, butyl acrylate is preferably used.

  The above polystyrene-based resins may be used alone or in combination of two or more.

  The molecular weight of the polystyrene-based resin can be 100,000 or more, preferably 150,000 or more in terms of mass average molecular weight (Mw). The upper limit of the mass average molecular weight (Mw) can be 500,000, preferably 400,000, and more preferably 300,000. If the molecular weight of the polystyrene-based resin is 100,000 or more, it is preferable without any defects that cause deterioration of the film. Furthermore, if the molecular weight of the polystyrene-based resin is 500,000 or less, there is no need to adjust the flow characteristics and there are no defects such as a decrease in extrudability, which is preferable.

  In the present invention, the polycarbonate resin that can be used as the thermoplastic resin (B) is preferably an aromatic polycarbonate resin. The aromatic polycarbonate resin may be either a homopolymer or a copolymer. In addition, the aromatic polycarbonate resin may have a branched structure, a linear structure, or a mixture of a branched structure and a linear structure.

  The aromatic polycarbonate resin can be produced using any known method such as a phosgene method, a transesterification method, or a pyridine method. Below, the manufacturing method of the aromatic polycarbonate-type resin by the transesterification method is demonstrated as an example.

  The transesterification method is a production method for performing melt transesterification polycondensation by adding a divalent phenol and a carbonic acid diester to a basic catalyst, and further adding an acidic substance that neutralizes the basic catalyst. 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, μ-cresyl carbonate, dinaphthyl carbonate, bis (biphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, and dicyclohexyl carbonate. Can be mentioned. Of these, diphenyl carbonate is particularly preferably used.

  The above aromatic polycarbonate resin has a mass (weight) average molecular weight of usually 10,000 or more, preferably 20,000 or more, and 100,000 or less, considering the balance between mechanical properties and molding processability. Preferably, 50,000 or less is used. If the mass (weight) average molecular weight is 10,000 or more, the mechanical strength of the resulting aromatic polycarbonate resin will not decrease, and if the upper limit is 100,000, an appropriate melt viscosity can be obtained. Therefore, the moldability can be maintained and the polymerization can be performed in a relatively short time, which is preferable from the viewpoint of production cycle and cost. In addition, in the film of this invention, you may use an aromatic polycarbonate-type resin individually by 1 type or in mixture of 2 or more types.

  When a polyolefin resin is used as the thermoplastic resin (B), the specific gravity of the entire film including the thermoplastic resin (B) is less than the polyester resin (A) because the polyolefin resin has a lower specific gravity than the polyester resin (A). It can be made smaller than a single film. Therefore, it is preferable to use a polyolefin resin as the thermoplastic resin (B).

  Examples of polyolefin resins that can be used in the present invention include polyethylene resins, polypropylene resins, ethylene copolymers such as ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-methyl acrylate copolymers. , Polymethyl terpene, or a mixed resin thereof. Especially, it is preferable to use a polyethylene-type resin, a polypropylene-type resin, or these mixtures from a viewpoint of a heat contraction rate and a moldability. There are various types of polyethylene resins and polypropylene resins depending on the polymerization method and copolymerization component, and the range is not particularly limited. Preferred types are shown below.

The polyethylene resin that can be used in the present invention is usually a high density polyethylene resin (HDPE) having a density of 0.94 g / cm ³ or more and 0.97 g / cm ³ or less, and a density of 0.92 g / cm ³ or more. Examples include medium density polyethylene resin (MDPE) of 94 g / cm ³ or less, low density polyethylene resin (LDPE) having a density of less than 0.92 g / cm ³ , and linear low density polyethylene resin (LLDPE). Among these, linear low density polyethylene resin (LLDPE) is preferably used from the viewpoint of stretchability, impact resistance of the film, transparency, and the like.

  Examples of the linear low density polyethylene resin (LLDPE) include a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, preferably 4 to 12 carbon atoms. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-1-butene, 4- Examples thereof include methyl-1-pentene. Among these, 1-butene, 1-hexene, and 1-octene are preferably used. Moreover, you may use the alpha olefin to copolymerize individually by 1 type or in combination of 2 or more types.

Preferred examples density of the polyethylene resin, the lower limit is preferably 0.800 g / cm ³ or more, more preferably 0.850 g / cm ³ or more, more preferably 0.900 g / cm ³ or more, the upper limit is , preferably 0.950 g / cm ³ or less, more preferably 0.940 g / cm ³ or less, more preferably 0.930 g / cm ³ or less. In the case of a heat-shrinkable film, if the density is 0.800 g / cm ³ or more, the waist (rigidity at room temperature) and heat resistance of the whole film are not significantly lowered, which is practically preferable. On the other hand, if the density is 0.950 g / cm ³ or less, the drawability at a low temperature is maintained, and a heat shrinkage rate in a practical temperature range (about 70 ° C. or more and about 90 ° C. or less) can be sufficiently obtained.

  As the polyethylene resin, those having a melt flow rate (MFR: JIS K7210, temperature: 190 ° C., load: 21.2 N) of 0.1 g / 10 min to 10 g / 10 min are preferably used. If the MFR is 0.1 g / 10 min or more, the extrudability can be satisfactorily maintained. On the other hand, if the MFR is 10 g / 10 min or less, it is difficult to cause unevenness in film thickness and mechanical strength, which is preferable.

  Next, examples of the polypropylene resin that can be used in the present invention include homopropylene resin, random polypropylene resin, block polypropylene resin, and propylene-ethylene rubber. Among these, a homopropylene resin capable of efficiently forming dispersed domains or pores when mixed with the polyester resin (A) is preferable, and a highly crystalline homopolypropylene resin is particularly preferably used.

  In the random polypropylene resin, the α-olefin to be copolymerized with propylene preferably includes those having 2 to 20 carbon atoms, more preferably those having 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene. 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like. In the present invention, from the viewpoints of stretchability, heat shrinkage characteristics, impact resistance, transparency, rigidity, and the like of the film, random polypropylene having an ethylene unit content of 2% by mass to 10% by mass as the α-olefin is particularly preferable. Preferably used. Moreover, you may use the alpha olefin to copolymerize individually by 1 type or in combination of 2 or more types.

  The melt flow rate (MFR) of the polypropylene resin is 0.5 g / 10 min or more, preferably 1.0 g / 10 min or more under the conditions of JIS K7210, temperature: 230 ° C., load: 21.2 N, And it is 15 g / 10min or less, Preferably it is 10 g / 10min or less.

  More specifically, commercially available products of the above-mentioned polyolefin resin include, as polyethylene resins, trade names “Novatech HD, LD, LL”, “Kernel”, “Toughmer A, P” (Nippon Polyethylene Co., Ltd.), “ Suntech HD, LD (Asahi Kasei Life & Living Co., Ltd.), HIZEX, ULTZEX, EVOLUE (Mitsui Chemicals Co., Ltd.), More Tech (Idemitsu Kosan Co., Ltd.), UBE Examples include polyethylene, UMERIT (manufactured by Ube Industries, Ltd.), NUC polyethylene, Nack Flex (manufactured by Nippon Unicar Co., Ltd.), and Enage (manufactured by Dow Chemical Co., Ltd.). Commercially available polypropylene resins include trade names “Novatech PP”, “WINTEC”, “Toughmer XR” (manufactured by Nippon Polypro), “Mitsui Polypro” (manufactured by Mitsui Chemicals), “Sumitomo Nobren”, “ “Tuff Selenium”, “Excellen EPX” (manufactured by Sumitomo Chemical Co., Ltd.), “IDEMITSU PP”, “IDEMITSU TPO” (manufactured by Idemitsu Kosan Co., Ltd.), “Adflex”, “Adsyl” (manufactured by Sun Aroma Co., Ltd.) Can be mentioned. Moreover, "TPX" (made by Mitsui Chemicals, Inc.) is mentioned as a commercial item of a polymethylpentene resin. These can be used alone or in admixture of two or more.

  Since the thermoplastic resin (B) is incompatible with the polyester resin (A), when the polyester resin (A) is contained more than the thermoplastic resin (B), the polyester resin (A) is a sea part, That is, when the matrix is formed, the thermoplastic resin (B) forms an island portion, that is, a dispersed domain, and the thermoplastic resin (B) is contained more than the polyester resin (A), the polyester resin (A) Form a dispersed domain, and the thermoplastic resin (B) forms a matrix. Details of the distributed domain will be described later.

  In the film of the present invention, when the polyester resin (A) or the thermoplastic resin (B) is contained more in the resin composition than the thermoplastic resin (B) or the polyester resin (A), the polyester resin In the resin (A) or the thermoplastic resin (B), the thermoplastic resin (B) or the polyester-based resin (A) forms a dispersion domain, and forms a sea-island structure as a whole film. When this resin composition is formed into a sheet and further stretched in at least one direction, it is a matrix due to the difference between E ′ of the polyester resin (A) and E ′ of the thermoplastic resin (B) at the stretching temperature. Peeling occurs at the interface between the polyester-based resin (A) or thermoplastic resin (B) and the thermoplastic resin (B) or polyester-based resin (A) that is the dispersion domain, and pores can be formed. Here, “E ′” refers to a storage elastic modulus at 80 ° C. when measured at a frequency of 10 Hz and a strain of 0.1%.

  In the film of the present invention, the mass ratio of the polyester resin (A) and the thermoplastic resin (B) incompatible with the polyester resin (A) is in the polyester resin (A) or the thermoplastic resin (B). The dispersion domain of the desired thermoplastic resin (B) or polyester-based resin (A) can be appropriately adjusted. Preferably, the mass ratio (A / B) of the polyester-based resin (A) and the thermoplastic resin (B) is adjusted in the range of 99/1 to 1/99, more preferably in the range of 90/10 to 10/90. Preferably, it is in the range of 80/20 to 20/80.

  If the content of the thermoplastic resin (B) that is incompatible with the polyester resin (A) is within the above range, dispersed domains or pores can be formed, and the function of improving light-shielding properties and breakage resistance can be exhibited. Can do.

<Compatibilizer (C)>
The film of the present invention has a polyester-based resin (A) because of poor dispersion of the thermoplastic resin (B), pore formation at the time of stretching, stretched film thickness, non-uniformity of light shielding properties, and improvement of film appearance. ) And the thermoplastic resin (B).

  The compatibilizing agent (C) used in the present invention is not particularly limited as long as it improves the compatibility of the polyester resin (A) and the thermoplastic resin (B), but is reactive to the polyester resin (A). Alternatively, a resin having both a site having affinity and a site having reactivity or affinity for the thermoplastic resin (B) is preferably used.

  Here, when the polyester resin (A) is a polylactic acid resin, the compatibilizer (C) has a highly reactive functional group or a functional group capable of reacting with the polylactic acid resin with respect to the polylactic acid resin. It is preferable to have. Examples of functional groups having such properties include acid anhydride groups, carboxylic acid groups, carboxylic acid ester groups, carboxylic acid chloride groups, carboxylic acid amide groups, carboxylic acid groups, sulfonic acid groups, and sulfonic acid ester groups. , Sulfonic acid chloride groups, sulfonic acid amide groups, sulfonic acid groups, epoxy groups, amino groups, imide groups, or oxazoline groups, among others, acid anhydride groups, carboxylic acid groups, or carboxylic acid esters Groups and the like.

  Further, when a polyolefin resin is used as the thermoplastic resin (B), the compatibilizer (C) has a linear or branched saturated hydrocarbon moiety having an affinity for the polyolefin resin as a main chain, block chain, graft It is preferable to have the chain.

  Furthermore, other preferred resins that can be used as the compatibilizer (C) include soft PO resins, copolymers of styrene hydrocarbons and conjugated diene hydrocarbons, or hydrogenated resins thereof. . Specific examples include soft linear low density polyethylene resin, low crystalline polypropylene resin, ethylene-vinyl acetate copolymer, etc., as soft PO resin, and styrene hydrocarbon and conjugated diene hydrocarbon. Examples of the copolymer include a styrene-butadiene copolymer, a styrene-isoprene copolymer, a styrene-ethylene-butadiene copolymer, a styrene-ethylene-propylene copolymer, and a styrene-ethylene-butylene copolymer.

  The content of the compatibilizing agent (C) is 3% by mass or more, preferably 5% with respect to 100% by mass of the mixed resin of the polyester resin (A), the thermoplastic resin (B) and the compatibilizing agent (C). It is desirable that the content is at least 7 mass%, more preferably at least 7 mass%, and at most 20 mass%, preferably at most 15 mass%, more preferably at most 12 mass%. If the content of the compatibilizer (C) is 3% by mass or more, the addition effect of the compatibilizer (C) is obtained to some extent, and if it is 20% by mass or less, the shrinkage characteristics, rigidity, and void forming ability are affected. Never give.

  Specific products of the compatibilizing agent (C) having a polar group that has high affinity or can react with the polylactic acid resin and is compatible with the polyolefin resin include acid-modified polyolefin resins. “Admer” (Mitsui Chemicals), “Modic” (Mitsubishi Chemical), “Modiper” (Nippon Yushi Co., Ltd.), “Bondyne” as an ethylene-vinyl acetate-maleic anhydride copolymer (Sumitomo Chemical) , “Bond first” (manufactured by Sumitomo Chemical Co., Ltd.) as an ethylene-glycidyl methacrylate copolymer, an ethylene-vinyl acetate-glycidyl methacrylate terpolymer, an ethylene-ethyl acrylate-glycidyl methacrylate terpolymer, Product names "Tuftec M" (Asahi Kasei Chemicals) and "Epofriend" (Daicel Chemical) as acid-modified styrene thermoplastic resins Copolymers of styrene-based hydrocarbons and conjugated diene-based hydrocarbons, or hydrogenated resins such as “Tuftec H” (manufactured by Asahi Kasei Chemicals), “Clayton” (manufactured by JSR Kraton Polymer), “Dynalon” (JSR) Product), “Septon” (manufactured by Kuraray Co., Ltd.), “Hiblar” (manufactured by Kuraray Co., Ltd.), “Tufprene” (manufactured by Asahi Kasei Chemicals Co., Ltd.) and the like.

<Filler (D)>
The film of the present invention includes the incompatible thermoplastic resin (B) in the polyester resin (A), thereby forming dispersed domains and pores in the film, thereby suppressing light transmittance (that is, The light transmittance can be further suppressed by further containing a filler (D).

  The filler (D) may be either an inorganic filler or an organic filler as long as it can impart light-shielding properties to the film. Inorganic fillers include calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide, zinc oxide, magnesium hydroxide, calcium oxide, magnesium oxide , Titanium oxide, alumina, mica, asbestos powder, shirasu balloon, zeolite, silicate clay and the like, and calcium carbonate, talc, clay, silica, diatomaceous earth, barium sulfate and the like are particularly preferable. Examples of the organic filler include cellulose powders such as wood powder and pulp powder. These may be used alone or as a mixture of two or more.

  It is preferable to use a filler (D) having a large refractive index difference from the polyester resin (A) as a base resin constituting the film, that is, an inorganic filler having a large refractive index. Specifically, calcium carbonate, barium sulfate, titanium oxide, or zinc oxide having a refractive index of 1.6 or more is preferably used, and among these, titanium oxide is more preferably used. By using titanium oxide, it absorbs the wavelength in the 230 to 380 nm ultraviolet range, which deteriorates the contents, so that the light shielding property of the film can be imparted with a smaller filling amount, and the effect can be obtained even with a thin wall. be able to.

  Examples of the titanium oxide used in the film of the present invention include crystalline titanium oxides such as anatase type titanium oxide and rutile type titanium oxide. From the viewpoint of increasing the difference in refractive index from the base resin, titanium oxide having a refractive index of 2.7 or more is preferable. For example, a crystal form of rutile titanium oxide is preferably used.

  Among titanium oxides, it is possible to minimize the yellowness of the appearance by using high-purity titanium oxide. High-purity titanium oxide is titanium oxide having a small light absorption capability for visible light, and means a material having a small content of colored elements such as vanadium, iron, niobium, copper, and manganese. In the present invention, titanium oxide having a vanadium content of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less is referred to as “high purity titanium oxide”. From the viewpoint of reducing the light absorption ability of high-purity titanium oxide, it is preferable to reduce iron, niobium, copper, manganese, etc., which are other coloring elements contained in titanium oxide.

  In the film of the present invention, titanium oxide and other fillers can be used in combination. In addition, in order to improve the dispersibility of the filler (D) in the polyester resin (A) and the thermoplastic resin (B), a silicone compound, a polyhydric alcohol compound, You may use what gave surface treatment with an amine compound, a fatty acid, fatty acid ester, etc.

  Examples of the surface treatment agent include at least one selected from the group consisting of at least one inorganic compound selected from the group consisting of alumina, silica, zirconia, and the like, a siloxane compound, a silane coupling agent, a polyol, and polyethylene glycol. These organic compounds can be used. Moreover, you may use combining these inorganic compounds and organic compounds.

  The size of the filler (D) used in the present invention is such that, when titanium oxide is used, the particle diameter is equivalent to a circle equivalent diameter of 0.1 μm or more, preferably 0.2 μm or more, and 1 μm or less, preferably 0.5 μm. The following is desirable. If the particle diameter of the titanium oxide is 0.1 μm or more in terms of the equivalent circle diameter, the dispersibility of the polyester resin (A) or the mixed resin of the polyester resin (A) and the thermoplastic resin (B) is good and homogeneous. Can be obtained. Moreover, if the particle diameter of titanium oxide is 1 μm or less in terms of the equivalent circle diameter, the interface between the polyester resin (A) or the mixed resin of the polyester resin (A) and the thermoplastic resin (B) and the titanium oxide is dense. Since it is formed, the light shielding property can be further improved.

  The content of the filler (D) contained in the film of the present invention is the resin composition (polyester resin (A), thermoplastic resin constituting the film, considering the light shielding properties, mechanical properties, productivity, etc. of the film. Mixed resin composition comprising resin (B) and compatibilizer (C), and in the case of containing soft component (E), mixed resin composition further containing soft component (E). 0 parts by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and 40 parts by mass or less, preferably 30 parts by mass or less, more preferably 25% by mass or less. When the film of this invention has a void | hole, a filler (D) will bear the auxiliary | assistant role of a light-shielding function. At that time, by setting the content of the filler (D) to 40 parts by mass or less, functions, rupture resistance, and shrinkage characteristics required as a heat shrinkable film can be ensured.

<Soft component (E)>
The film of the present invention preferably contains a soft component (E) in order to improve fracture resistance. As such a soft component (E), other than the polyester resin (A) constituting the film, that is, other types of aliphatic polyesters and aromatics different from the polyester resin used as the polyester resin (A) Aliphatic aliphatic polyester, copolymer of diol, dicarboxylic acid and lactic acid resin, core-shell structure rubber, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic Acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMA), ethylene-methyl acrylate copolymer (EAMA), ethylene-methyl methacrylate copolymer (EMMA), styrene-isobutylene copolymer Copolymer (SIS), styrene-butadiene copolymer (SBS), styrene-ethylene-butadiene Copolymer (SEBS), styrene-based elastomers such as acid-modified SEBS is preferably used. Among them, aliphatic polyesters, aromatic aliphatic polyesters, copolymers of diols, dicarboxylic acids, and lactic acid resins, core-shell structure rubbers (MBS, silicone-acrylic), and ethylene-vinyl acetate copolymers (EVA) And the like are more preferably used.

  The content of the soft component (E) is 5% by mass with respect to 100% by mass of the mixed resin of the polyester resin (A), the thermoplastic resin (B), the compatibilizer (C), and the soft component (E). Above, preferably 7% by mass or more, more preferably 10% by mass or more, and 50% by mass or less, preferably 30% by mass or less, and more preferably 20% by mass or less. If the content of the soft component (E) is 5% by mass or more, the addition effect of the soft component (E) is obtained to some extent, and if it is 50% by mass or less, the shrinkage characteristics, rigidity, and void forming ability are affected. There is nothing.

  The film of the present invention has the above polyester-based resin (A) for the purpose of reducing bulk specific gravity and the like within a range that does not impair various properties required as a surface layer, such as printability, solvent sealability, and adhesion resistance. ) And other resins than the thermoplastic resin (B). Examples of such a resin include acrylic resins, amide resins, aliphatic polyester resins, aromatic polyester resins, aliphatic aromatic polyester resins, and the like.

  In addition, the film of the present invention may be a plasticizer, a heat stabilizer, an antioxidant, a UV absorber, a light stabilizer, a pigment, a colorant, a lubricant, and a nucleating agent as long as the effects of the present invention are not impaired. An additive such as a hydrolysis inhibitor may be added.

<Method for producing light-shielding heat-shrinkable film>
The film of this invention can be manufactured by a well-known method using the said mixed resin. The form of the film may be either a flat form or a tube form, but the flat form is preferred from the viewpoint of productivity (a few products can be taken in the width direction of the original film).

  As a method for producing a flat laminated film, for example, a resin is melted using a plurality of extruders, co-extruded from a multi-manifold type T die or a T die using a feed block, and then cooled with a chilled roll. Examples of the method include solidification, roll stretching in the vertical direction, tenter stretching in the horizontal direction, annealing, and cooling. Moreover, after obtaining the single-layer film of each layer separately, a well-known method can be employ | adopted, such as laminating | stacking by a heat | fever lamination and joining with an adhesive agent. When printing is performed, a film can be obtained by performing corona discharge treatment and winding with a winder. Moreover, the method of cutting open the film manufactured by the tubular method and making it planar is also mentioned.

  The stretching ratio in the stretching is such that the longitudinal direction is 2 to 10 times, the transverse direction is 2 to 10 times, and preferably 3 to 6 times in the longitudinal direction, for applications such as overlapping and shrinking in two directions. Hereinafter, the horizontal direction is about 3 to 6 times. On the other hand, in applications that shrink mainly in one direction, such as for heat-shrink labels, the direction corresponding to the main shrinkage direction is 2 to 10 times, preferably 3 to 7 times, more preferably 3 to 5 times. The direction orthogonal to it is 1 to 2 times (1 time indicates that the film is not stretched), preferably 1.01 to 1.5 times, substantially uniaxially stretched. It is desirable to select a magnification ratio in the category. A biaxially stretched film stretched at a stretch ratio within the above range does not have an excessively large thermal shrinkage rate in the direction orthogonal to the main shrinkage direction.For example, when used as a shrinkage label, It is preferable because the so-called vertical shrinkage phenomenon, in which the film is thermally contracted in the vertical direction, can be suppressed.

  The stretching temperature needs to be changed depending on the glass transition temperature of the resin to be used and the properties required for the heat-shrinkable film, but is generally 60 ° C. or higher, preferably 70 ° C. or higher, and the upper limit is 100 ° C. or lower, preferably 90 ° C. It is controlled within the following range.

  If the stretching temperature is 60 ° C. or higher, the elastic modulus of the raw material can be prevented from becoming too high during the stretching process, so that good stretchability can be obtained, and film breakage and thickness unevenness can be suppressed. On the other hand, when the stretching temperature is 100 ° C. or lower, desired shrinkage characteristics can be expressed, and the stretchability of the thermoplastic resin (B) is suppressed from increasing, that is, the polyester resin (A) and the thermoplastic resin (B ) And the storage elastic modulus (E ′) difference can be ensured, and peeling at the interface is promoted, and sufficient pores are obtained.

  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.

  In addition, the film of the present invention can be subjected to surface treatment such as corona treatment, printing, coating, vapor deposition, and surface treatment as needed, and further, bag making processing and perforation processing using various solvents and heat sealing. .

<Film structure>
The layer structure of the film of the present invention may be a single layer, or as a laminated structure for the purpose of imparting surface functional properties such as slipperiness, heat resistance, solvent resistance, and easy adhesion to the film surface. Also good. That is, even a laminate having at least one layer containing a polyester resin (A) as a main component and a thermoplastic resin (B), a compatibilizer (C), and a filler (D) as other components. Good. For example, in the (I) layer containing the polyester resin (A), the thermoplastic resin (B), the compatibilizer (C), and the filler (D), the (II) layer having a different resin composition or additive, When the (III) layer having a different resin composition or additive is laminated on both the (I) layer and the (II) layer, the following layer configurations are mentioned. Moreover, the lamination ratio of each layer can be adjusted timely according to a use and the objective.
(I) / (II)
(II) / (I) / (II)
(II) / (I) / (III)
(II) / (I) / (III) / (II)
(II) / (III) / (I) / (III) / (II)

  The laminated film of the present invention may further be provided with an adhesive layer for the purpose of improving the adhesion between the layers. The resin constituting the adhesive layer is not particularly limited as long as it is a resin capable of exhibiting adhesiveness, but the resin exemplified in the compatibilizing agent (C) can be suitably used as the adhesive resin.

  In addition, when the film of the present invention contains pores, in addition to this layer, the (II) layer having no pores or having a low pore content is disposed, thereby providing a printability, solvent, Sealability can be improved. Furthermore, the total thickness of the film of the present invention is not particularly limited, whether it is a single layer or a laminate, but it is preferably thinner from the viewpoints of shrinkage workability, raw material costs, and the like. Specifically, the total thickness of the stretched film is preferably 150 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less. Further, the lower limit of the total thickness of the film is not particularly limited, but is preferably 20 μm or more in consideration of the handleability of the film.

  The stretching direction in the stretching step can be appropriately selected depending on the intended use. However, since the film of the present invention has a structure in which the dispersion domain of the component (B) is elongated in the MD direction as described later, it is perpendicular to the stretching direction. It is preferable that pores can be easily formed by stretching in the direction, that is, the TD direction.

Moreover, in the case of uniaxial stretching, if the weak stretching of about 1.01 times to 1.8 times is applied in the direction orthogonal to the main shrinkage direction of the film as necessary, the mechanical properties of the obtained light-shielding heat-shrinkable film are Since it is improved, it is more preferable. In the present specification, the “main shrinkage direction” means a direction in which stretching is large between the longitudinal direction and the transverse direction. For example, in the case of mounting on a bottle, the direction corresponds to the outer circumferential direction. The “direction orthogonal to the main shrinkage direction” refers to a direction orthogonal to the direction in which stretching is large.

<Aspect ratio of dispersed domain made of thermoplastic resin (B)>
By the way, since the cooling roll used by the said film manufacturing method exists under the said extruder, the state by which the film extruded from the said extruder was extended a little by its own weight by the time it reached a cooling roll become. At this time, the case where the thermoplastic resin (B) is contained in the polyester-based resin (A) will be described as an example. The film is in a high temperature state because it is extruded from the extruder, and the film is thermoplastic. When the resin (B) is contained, not only the matrix made of the polyester resin (A) but also the dispersion domain made of the thermoplastic resin (B) is extended in the direction (flow direction) orthogonal to the main shrinkage direction. For this reason, especially the dispersion domain which consists of a thermoplastic resin (B) will be in the state extended | stretched in the flow direction (direction orthogonal to a film main shrinkage | contraction direction). By adjusting the aspect ratio of the dispersion domain made of the thermoplastic resin (B) at this time, it becomes possible to improve the fracture resistance of the film. It is desirable that the aspect ratio of the dispersed domain is adjusted to be greater than 1, preferably 3 or more, more preferably 5 or more, and 50 or less, preferably 40 or less, more preferably 35 or less. If the aspect ratio of the dispersion domain is larger than 1, pores are likely to be generated when stretched in a direction perpendicular to the flow direction, and if the aspect ratio is 50 or less, the dispersion domain becomes too fine and stretched. Is also preferable because it is difficult to cause a problem that it is difficult to generate holes. In addition, when a polyester-type resin (A) is contained in a thermoplastic resin (B), it is the same as the above except that said resin becomes reverse.

<Light transmittance>
The film of the present invention is such that light rays are refracted and reflected at the interface between the polyester-based resin (A), the thermoplastic resin (B) and the filler (D) and at the interface with the pores, and the mixed resin and filler. By partially absorbing the light, it has opaque white light blocking properties (light blocking properties). 230 nm or more and 800 nm or less (ultraviolet-visible region) combining the ultraviolet region with a wavelength of 230 nm or more and less than 380 nm that may deteriorate or alter the contents, and the visible region with a wavelength of 380 nm or more and 800 nm or less related to the concealability of the contents The light transmittance measured in accordance with JIS K7015 is essential to be 40% or less at any wavelength, preferably 30% or less, and more preferably 25% or less. If the light transmittance is 40% or less, the light-shielding property is sufficient, and it is difficult to develop a problem that the contents are not protected and concealed.

  In particular, for the purpose of protecting the contents, it is essential that the average of the wavelength range is 20% or less in the ultraviolet region having a wavelength of 230 nm or more and less than 380 nm, which degrades or alters the contents. It is preferable that it is 5% or less.

  In the film of the present invention, in order to adjust the light transmittance at a wavelength of 230 nm or more and a wavelength of 800 nm or less to the above range, the resin composition constituting the film is adjusted to the composition and content of the resin as described in the present invention. At the same time, the stretching temperature can be set lower, or the stretching ratio can be increased. For example, when it is desired to further reduce the light transmittance, the content of the thermoplastic resin (B) is increased, the content of the filler (D) is increased, the stretching ratio is increased, the stretching temperature is decreased, etc. There is a way. Furthermore, in order to adjust the light transmittance in the ultraviolet region of 230 nm or more and less than 380 nm to the above range, it is preferable to use titanium oxide as the filler (D). By using titanium oxide as the filler (D), the light transmittance in the ultraviolet region of 230 nm or more and less than 380 nm can be reduced to 2% or less.

<Heat shrinkage>
When the film of the present invention is immersed in warm water at 80 ° C. for 10 seconds, the heat shrinkage rate in the main shrinkage direction is 20% or more, preferably 30% or more, more preferably 40% or more, and 80% or less, Preferably it is 70% or less. For example, a heat-shrinkable film applied to a shrinkage label for a PET bottle varies depending on its shape, but generally requires a heat shrinkage rate of about 20% to 70%. This is because it is possible to cope with the problem.
In the present specification, the “main shrinkage direction” means a direction in which the thermal shrinkage rate is large in the longitudinal direction (longitudinal direction) of the film and the lateral direction (width direction) of the film. Means a direction corresponding to the outer circumferential direction, and “orthogonal direction” means a direction perpendicular to the main contraction direction.

The shrinkage processing machine that is most commonly used industrially for labeling of PET bottles is generally called a steam shrinker that uses steam as a heating medium for shrinking. 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. Furthermore, with the recent increase in the speed of the labeling process, there has been an increasing demand for shrinking quickly at a lower temperature. In consideration of such industrial productivity, a film having a heat shrinkage rate of at least 20% under the above conditions is preferable because it can sufficiently adhere to the object to be coated within the shrinkage processing time.

  When the film of the present invention is used as a heat shrink label, the heat shrink rate in the direction perpendicular to the main shrink direction is preferably 10% or less when immersed in warm water at 80 ° C. for 10 seconds. % Or less is more preferable, and 5% or less is further preferable. If the film has a thermal shrinkage rate of 10% or less in the direction perpendicular to the main shrinkage direction, the dimension itself in the direction perpendicular to the main shrinkage direction after shrinkage may be shortened, or the printed pattern or character distortion after shrinkage may occur. In the case of a square bottle, it is preferable because troubles such as vertical sink are unlikely to occur.

<Fracture resistance>
The rupture resistance of the film of the present invention is evaluated by the tensile rupture elongation, and in a tensile test under a 0 ° C. environment, the elongation is 100% or more in the film take-off (flow) direction (MD), particularly for label applications, It is necessary to be 150% or more, more preferably 200% or more. If the tensile elongation at break in an environment of 0 ° C. is 100% or more, such a problem that the film is not easily broken at the time of printing and bag making is preferable. Further, even when the tension applied to the film increases as the speed of processes such as printing and bag making increases, it is preferable that the tensile elongation at break is 200% or more because it is difficult to break. The upper limit is not particularly limited, but considering the current process speed, it is considered that about 500% is sufficient. On the other hand, when trying to give too much elongation, the rigidity (tensile modulus) of the film decreases. It tends to end up.

<Application>
Since the film of the present invention contains a thermoplastic resin (B) that is incompatible with the polyester resin (A), light is emitted at the interface between the polyester resin (A) or the thermoplastic resin (B) and air. Is refracted and reflected, and further contains a filler (D), thereby giving an opaque white-like appearance as a whole. Therefore, it is particularly suitable for applications that require not only excellent design properties but also light shielding properties. Furthermore, when it has a void | hole, heat-conduction efficiency falls rather than a normal thermoplastic resin, for example, it is suitable for the use as which heat insulation and heat retention, such as a label for hot beverages, are calculated | required. Furthermore, when it has a void | hole, it is excellent also in cushioning properties and it is suitable also for protection uses, such as a fragile thing and a fragile thing.

<Molded products, heat-shrink labels and containers>
The film of the present invention is excellent in printability of the film, light shielding properties, high rigidity, rupture resistance, film appearance, shrink finish, etc., so its use is not particularly limited, if necessary, By forming a printing layer, a vapor deposition layer and other functional layers, it can be used as various molded products such as trays, lunch boxes, prepared food containers, and dairy products containers.

  In particular, when the film of the present invention is used as a heat-shrinkable label for food containers (for example, soft drinks or food PET bottles, glass bottles, preferably PET bottles), a complicated shape (for example, a cylinder with a constricted center, corners, etc.) A rectangular column, pentagonal column, hexagonal column, etc.) can be adhered to the shape, and a container with a beautiful label without wrinkles or avatars can be obtained. The obtained molded product can be used as a container or the like. The molded article and container of the present invention can be produced by using a normal molding method.

  Since the film of the present invention has excellent low-temperature shrinkage and shrinkage finish properties, in addition to the heat-shrinkable label material of a plastic molded product that deforms when heated to a high temperature, the coefficient of thermal expansion, water absorption, etc. Material very different from the film, for example, polyolefin resin such as metal, porcelain, glass, paper, polyethylene, polypropylene, polybutene, polymethacrylate resin, polycarbonate resin, polyester resin such as polyethylene terephthalate, polybutylene terephthalate, It can be suitably used as a heat-shrink label material for a package (container) using at least one selected from polyamide resins as a constituent material.

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

  The present invention will be described below with reference to examples. Here, the film take-up (flow) direction is described as MD, and the direction orthogonal thereto is described as TD.

[raw materials]
The raw materials used in each example and comparative example are as follows.

(Polyester resin (A))
Mitsui Chemicals, Inc .: Polylactic acid resin (trade name: LACEA H-440, L-form / D-form weight = 95.8 / 4.2, hereinafter abbreviated as “PLA1”)
Nature Works: Polylactic acid resin (trade name: NatureWorks 4060, L-form / D-form weight = 89/11, hereinafter abbreviated as “PLA2”)
In both Examples and Comparative Examples, the intermediate layer was PLA1 / PLA2 = 3/2 (D amount 6.92%), and the front and back layers were PLA1 / PLA2 = 4/1 (D amount 5.56%). .

(Thermoplastic resin (B))
-Nippon Polypro Co., Ltd .: Polypropylene resin (trade name: FY6H, elastic modulus at 80 ° C .: 0.57 GPa, MFR = 1.9 g / 10 minutes, hereinafter abbreviated as “FY6H”)

(Compatibilizer (C))
JSR Corporation: Acid-modified SEBS (trade name: Dynalon, hereinafter abbreviated as “DR”)

(Filler (D))
DuPont: Titanium oxide (trade name: R104, hereinafter abbreviated as “FL”)

(Soft component (E))
Kaneka Corporation: MBS Rubber (trade name: Kane Ace B-561, Core Shell Structure MBS, hereinafter abbreviated as “B561”)

[Preparation of sample film]
In the monolayer film (Example 1 and Comparative Example 1), the polyester resin (A), the polyolefin resin (B), the compatibilizer (C), the filler (D), at the blending ratio shown in Table 1. The mixed resin obtained by mixing the soft component (E) is put into a twin-screw extruder (manufactured by Mitsubishi Heavy Industries, Ltd.), melted and mixed at a set temperature of 210 ° C, and extruded from a die having a set temperature of 220 ° C. Thereafter, the film was taken up with a cast roll at 50 ° C. and cooled and solidified to obtain an unstretched film.
In addition, in the laminated film (Example 2, Comparative Examples 2 and 3), the raw materials of the intermediate layer and the front and back layers were blended as shown in Table 1 using a twin screw extruder (Mitsubishi Heavy Industries, Ltd.). The mixture was kneaded at 210 ° C. and 100 rpm, extruded into a strand shape, rapidly cooled in a water tank, and then cut to produce pellets. They were put into a separate single-screw extruder (manufactured by Mitsubishi Heavy Industries, Ltd.) and coextruded from a two-type three-layer die. Thereafter, the film was taken up by a cast roll at 50 ° C. and cooled and solidified to obtain an unstretched film. Next, in both single-layer and laminated films, the obtained unstretched film was subjected to a film tenter (Mitsubishi Heavy Industries, Ltd.) at a preheating temperature of 80 ° C., a stretching temperature of 71 ° C., and a heat treatment temperature of 76 to 81 ° C. in the horizontal axis direction. The film was stretched 4.0 times, and a light-shielding heat-shrinkable film (films according to Examples 1 and 2 and Comparative Examples 1 to 3; hereinafter referred to as “sample films”) having a thickness of about 50 μm. .

[Measurement method and evaluation method]
The physical property values and evaluation in the experimental examples and comparative examples were measured and evaluated by the following methods.

<Light transmittance>
The obtained sample film was cut into a size of MD 30 mm × TD 30 mm, and a spectrophotometer (“U-4000”, manufactured by Hitachi, Ltd.) equipped with an integrating sphere was scanned from a wavelength of 220 nm to 800 nm with a scanning period of 0.5 nm. The light transmittance was measured. Table 1 shows the light transmittance at wavelengths of 315 nm and 550 nm.

<Fracture resistance>
In order to evaluate the manufacturing process of the film and the fracture resistance during use, the following measurements were performed. That is, the obtained sample film was cut into a size of MD 110 mm × TD 15 mm, and in accordance with JIS K6732, the ambient temperature was 23 ° C. at a tensile speed of 200 mm / min, and the MD of the sample film at an ambient temperature of 0 ° C. at a tensile speed of 100 mm / min. The tensile elongation was measured and the average value of 10 measurements is shown in Table 1.

<Heat shrinkage>
The sample film was cut into a size of MD100 mm × TD100 mm, immersed in an 80 ° C. hot water bath for 10 seconds, and the amount of shrinkage was measured. As the thermal shrinkage rate, a larger value of the ratio of the shrinkage amount to the original size before shrinkage, MD / TD, was expressed as a% value. The measurement results are shown in Table 1.

<Thickness unevenness>
About the document film, the thickness of 30 points | pieces was measured on the straight line in MD direction 100mm, and the standard deviation was calculated | required. At that time, the case where the standard deviation was 1 μm or less was evaluated as “◯”, the case where it exceeded 1 μm and 2 μm or less was evaluated as “Δ”, and the case where it exceeded 2 μm was evaluated as “X”. The evaluation results are shown in Table 1.

<Appearance unevenness>
When the sample film is held over a fluorescent lamp, “X” indicates that there is a clear unevenness, “△” indicates that the main unevenness is not observed visually, and “No” indicates that there is no unevenness. Evaluated as “◯”. The evaluation results are shown in Table 1.

From Table 1, the films according to Examples 1 and 2 show favorable values as general light-shielding heat-shrinkable films with respect to heat shrinkage, tensile elongation, and light transmittance. It can be seen that a film which is uniform as a whole and excellent in heat shrinkage characteristics, rupture resistance, light shielding properties and appearance is obtained.
On the other hand, the films according to Comparative Examples 1 to 3 in which the content of the compatibilizer is less than 3% by mass have unevenness in the thickness as a whole. It was done. From this, it can be seen that a film having excellent light-shielding properties, rupture resistance, shrinkage characteristics, thickness uniformity, and film appearance can be obtained by constituting the film in a composition within the range defined in the present invention.

  Since the film of this invention can have a polylactic acid-type resin as a main component as a polyester resin, it can reduce environmental impact. In addition, since it is a film excellent in light-shielding property, high rigidity, rupture resistance, shrinkage characteristics, thickness uniformity, film appearance, and film-forming properties, various shrink wrapping, shrink ties, shrink labels, etc. Can be used for

Claims (13)

The polyester resin (A), the thermoplastic resin (B) incompatible with the polyester resin (A), the compatibilizing agent (C), and the filler (D) are represented by the following (1) to (3 The non-stretched film contained in the relationship (1) is stretched in at least one direction, and has a shrinkage ratio in the main shrinkage direction of 20% or more when immersed in warm water at 80 ° C. for 10 seconds. Heat shrink film.
(1) Mass ratio of polyester resin (A) to thermoplastic resin (B) (A / B): 99/1 to 1/99
(2) Content of compatibilizing agent (C): 3% by mass or more and 20% by mass or less (3) filling with respect to the total amount of polyester resin (A), thermoplastic resin (B) and compatibilizing agent (C) Content of Agent (D): 0 to 40 parts by mass with respect to 100 parts by mass of the resin composition constituting the film The light-shielding heat-shrinkable film according to claim 1, wherein the polyester resin (A) is a polylactic acid resin. It contains a soft component (E) other than the polyester resin (A) and the thermoplastic resin (B), and the polyester resin (A), the thermoplastic resin (B), the compatibilizer (C), and the soft component ( The light-shielding heat-shrinkable film according to claim 1 or 2, wherein the content of the soft component (E) with respect to the total amount of E) is 5% by mass or more and 50% by mass or less. The light-shielding heat-shrinkable film according to any one of claims 1 to 3, wherein the thermoplastic resin (B) is at least one selected from the group consisting of polyolefin-based resins, polystyrene-based resins, and polycarbonate-based resins. 5. The average light transmittance in a wavelength range of 230 nm or more and less than 380 nm is 20% or less, and the average light transmittance in a wavelength range of 380 nm or more and 800 nm or less is 40% or less. Light-shielding heat shrink film. An acid-modified polyolefin resin, ethylene-acetic acid, wherein the compatibilizing agent (C) has a polar group that has high affinity or can react with the polyester resin (A) and is compatible with the thermoplastic resin (B). Vinyl-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate terpolymer, ethylene-ethyl acrylate-glycidyl methacrylate terpolymer, acid-modified styrene The light-shielding heat-shrinkable property according to claim 4 or 5, which is at least one selected from the group consisting of a thermoplastic resin, a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon, or a hydrogenated resin thereof. the film. Soft polyester (E) is an aliphatic polyester other than the polyester resin (A), aromatic aliphatic polyester, copolymer of diol, dicarboxylic acid and lactic acid resin, core-shell structure type rubber, ethylene-acetic acid At least one selected from the group consisting of vinyl copolymers, ethylene-ethyl acrylate copolymers, ethylene- (meth) acrylic acid copolymers, ethylene-methyl (meth) acrylate copolymers, and styrene elastomers. The light-shielding heat-shrinkable film according to any one of claims 4 to 6. The light-shielding heat-shrinkable film according to any one of claims 1 to 7, wherein the filler (D) is at least one selected from the group consisting of calcium carbonate, barium sulfate, titanium oxide, and zinc oxide. The filler (D) is titanium oxide, the average light transmittance in the wavelength range of 230 nm or more and less than 380 nm is 2% or less, and the average light transmittance in the wavelength range of 380 nm or more and 800 nm or less is 40% or less. The light-shielding heat-shrinkable film according to claim 8. A laminated film comprising at least one layer of the light-shielding heat-shrinkable film according to any one of claims 1 to 9. A molded article using the light-shielding heat-shrinkable film according to any one of claims 1 to 9 or the laminated film according to claim 10. The heat-shrink label which uses the light-shielding heat-shrink film in any one of Claim 1 to 9, or the laminated | multilayer film of Claim 10. A container formed by mounting the molded product according to claim 11 or the heat shrinkable label according to claim 12.