JP5269642B2 - Heat-shrinkable film, molded article using the heat-shrinkable film, heat-shrinkable label, and container using or fitted with the molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a film giving less burden to the environment, excellent in transparency and excellent in shrinking characteristics upon attaching a label and in transparency of the label after attached, and suitable to be used as a shrink package, a shrink-binding package, a shrink label or the like. <P>SOLUTION: The film contains, as a main component, a mixture resin of a polylactic acid-based resin and a polyacetal-based resin, wherein the mass ratio of the polylactic acid-based resin to the polyacetal-based resin is from 95/5 to 60/40, and the polylactic acid-based resin is preferably a copolymer of D-lactic acid and L-lactic acid, in a D/L ratio of D-lactic acid to L-lactic acid of larger than 5/95 and 15/85 or less, or 85/15 or more and less than 95/5. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention, heat shrinkage films, molded article using a heat-shrinkable film of Narabiniko, heat-shrinkable label, and relates the moldings or containers fitted with the label, and more particularly, transparency, during label attached Heat-shrinkable film, transparency after mounting , heat- shrinkable film suitable for uses such as shrink-wrapping, shrink-bound packaging and shrink-labeling, and molded articles using the heat-shrinkable film, heat-shrinkable labels, and The present invention relates to a container using a molded product or equipped with this label.

  Conventionally, various plastic materials such as polyethylene, polypropylene, polyester, polystyrene, polyethylene terephthalate, polyamide, polycarbonate, etc. are widely used as plastic materials for packaging materials, cards, containers, and others. When used, it is often difficult to obtain sufficient physical properties. For example, polylactic acid, which is a type of polyester resin, has the drawbacks that it is brittle and inferior in impact resistance, and it is known to improve its physical properties by mixing it with a soft resin.

  On the other hand, the effective use of exhaustible resources has recently been emphasized, and the use of renewable resources has become an important issue. Currently, the most noticeable solution is the use of plant-based plastics. This plant-derived plastic not only uses non-depleted resources, but can save exhaustible resources during plastic production, and also has excellent recyclability.

  Among these plant-derived plastics, polylactic acid resins are made from lactic acid obtained by fermentation of starch, can be mass-produced by chemical engineering, and have excellent transparency and rigidity. As an alternative material for polyester (polyethylene terephthalate), it has attracted attention in the field of film packaging materials and injection molding.

  However, when polylactic acid is used as the material for the heat-shrinkable label, it is rigid at room temperature, has low-temperature shrinkability, and has good natural shrinkage, but it is a very brittle material. There is a problem that sometimes contraction spots and wrinkles are likely to occur. In addition, the polylactic acid-based heat-shrinkable film also has a problem that when heated, crystallization proceeds and sufficient heat-shrinkage characteristics cannot be obtained.

  As means for solving the above problems, a film made of polylactic acid and a polyolefin compound (see Patent Document 1), a molded product made of polylactic acid and a modified olefin compound (see Patent Document 2) or a composition (see Patent Document 3). It has been known. Further, a molded product made of polylactic acid and syndiotactic polypropylene (see Patent Document 4), a polymer containing lactic acid as a main component, an aliphatic carboxylic acid, and an aliphatic polyester plasticizer containing a chain molecular diol as a main component. There is known a plasticized polylactic acid film (see Patent Document 5). Also, a biodegradable resin composition comprising polylactic acid and an epoxidized diene block copolymer (see Patent Document 6), a lactic acid polymer composition comprising polylactic acid, an aliphatic polyester, and polycaprolactone (Patent Document 7). And a method using a polylactic acid resin composition (see Patent Document 8) composed of crystalline polylactic acid and at least one rubber component selected from natural rubber and polyisoprene is known.

  However, when the above polycaprolactone, modified olefin compound, epoxidized diene block copolymer, natural rubber, polyisoprene, etc. are mixed with lactic acid resin, the impact resistance is improved, but as a result, transparency For example, it is difficult to say that the technique is sufficient for use in applications where it is necessary to check contents such as packaging materials.

  On the other hand, as a technique for modifying a polylactic acid resin without impairing transparency, a technique of blending a polyacetal resin (see Patent Document 9) is disclosed. However, since D-lactic acid in the polylactic acid resin is 95% or more or L-lactic acid is 95% or more, the crystallinity of polylactic acid is high, and a printing process or solvent for improving the design of the film was used. In the bag making process, it becomes difficult to develop printability and solvent sealability, and it is difficult to say that the technique is sufficient for use as a heat-shrinkable film. 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.

Moreover, the method (refer patent document 10) which improves transparency and slipperiness by mix | blending a polyacetal resin with a polylactic acid-type resin, and making it extend | stretch is disclosed. However, this technique is intended to reduce the crystallization temperature of the resin composition by blending a polyacetal resin with a polylactic acid-based resin, crystallize the obtained stretched film, and suppress the shrinkage rate. Therefore, it is different from the technology related to shrink film application, which mainly aims to develop heat shrinkability. As for slipperiness, gravure printing, which is a general printing method in the printing process mentioned above, prints through many rolls. For this reason, in the film described in the above-mentioned patent document, color misregistration of printing in the printing process, folding of the film itself, and the like occur, and it is difficult to say a technique sufficient for use as a heat shrinkable film. Further, in the attachment process to the cover, the roll film in a bag shape is cut, and the bag-like heat-shrinkable film is opened to be attached to the cover, so that the static friction coefficient is 0.6 or more. Opening defects are likely to occur. Furthermore, regarding transparency, which is one of the most important properties of shrink film together with heat shrinkability, transparency as a stretched film is good, but transparency when exposed to warm water or steam atmosphere Is not described, and it is difficult to think of a technique that satisfies the necessary characteristics as a heat shrinkable film that is mainly shrunk in a steam shrinker process.

JP 2005-68232 A JP 09-316310 A Japanese Patent Laid-Open No. 5-179110 JP-A-10-251498 JP 2000-191895 A JP 2000-219803 A JP 2001-031853 A JP 2003-183488 A JP 2003-113298 A JP 2004-107630 A

The present invention has been made in view of the above problems, and the problems of the present invention are that it has a low environmental load, has impact resistance, transparency, mechanical properties, slipperiness and design properties, and shrinkage properties. The object is to obtain a heat- shrinkable film suitable for applications such as excellent shrink packaging, shrink-bound packaging and shrink labels.

Another object of the present invention, shrink packaging, shrink bundling-packing, shrinkable label and the like applications Suitable before Symbol heat-shrinkable film molded article using a, a heat-shrinkable label and the moldings or heat-shrinkable label The purpose is to obtain a mounted container.

An object of the present invention, a mixed resin of polylactic acid resin and polyacetal resin containing as a main component, the mass ratio of the polylactic acid resin and the polyacetal resin is 95 / 5-60 / 40 film Can be solved by a heat-shrinkable film characterized by having a heat shrinkage ratio in the main shrinkage direction of 20% or more when immersed in warm water at 80 ° C. for 10 seconds. .

In the heat-shrinkable film of the present invention, the polylactic acid resin is a copolymer of D-lactic acid and L-lactic acid, or a mixed resin of the copolymer, and D / L of D-lactic acid and L-lactic acid. The ratio is preferably greater than 5/95 and not greater than 15/85, or not less than 85/15 and less than 95/5.

In the heat-shrinkable film of the present invention, the mixed resin contains a lubricant, and the content of the lubricant is 0.01% by weight or more and 0.2% by weight based on the total amount of the polylactic acid resin, the polyacetal resin and the lubricant. %, And the film has a static friction coefficient of 0.1 or more and 0.5 or less.

    The heat-shrinkable film of the present invention has a haze value of 8% or less in conformity with JIS K7105, and has two rectangular metal frames with a length of 130 mm, a width of 170 mm, and a width of 5 mm. It is preferable that the haze value based on JIS K7105 after being immersed in warm water of 80 ° C. for 20 minutes in a sandwiched state is 15% or less.

Another object of the present invention is solved by a molded product using the heat- shrinkable film of the present invention as a base material, a heat-shrinkable label, and a container using or mounting this molded product. be able to.

  According to the present invention, the polylactic acid resin is formed of a mixed resin containing a polylactic acid resin and a polyacetal resin in a predetermined ratio, and the polylactic acid resin is a copolymer of D-lactic acid and L-lactic acid, or a copolymer thereof. It is composed of a blended resin and contains a D / L ratio of D-lactic acid and L-lactic acid at a predetermined ratio, so that it has excellent transparency, impact resistance, mechanical characteristics, and secondary processing characteristics. Become. In particular, a heat-shrinkable film is preferable because a heat-shrinkable film having good heat-shrinkage characteristics when mounted on a container as a label and transparency after mounting can be obtained.

  Furthermore, according to the present invention, a molded product using the heat-shrinkable film suitable for applications such as shrink-wrapping, shrink-bound packaging and shrink-labeling, a heat-shrinkable label, and a container equipped with the molded product or heat-shrinkable label Can be provided.

It is the schematic of the instrument for measuring the haze value at the time of hot water immersion of the heat-shrinkable film of this invention.

  Hereinafter, a film, a stretched film, a heat-shrinkable film, a molded product, a heat-shrinkable label, and a container equipped with this molded product or heat-shrinkable label (hereinafter referred to as “the film of the present invention”, “the present invention”, respectively) The stretched film of the present invention, “the heat-shrinkable film of the present invention”, “the molded product of the present invention”, “the label of the present invention”, and “the container of the present invention”) will be described in detail.

  In the present specification, “main component” is intended to allow other components to be included as long as the action and effect of the resin constituting each layer is not hindered. Further, this term does not limit the specific content, but it is 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass, based on the total components of each layer. It is a component occupying the range of% or less.

  Further, in the present invention, the “film” is a flat product that is thin and has a small thickness instead of length and width, and is usually supplied in the form of a roll, including a sheet-like product. (See JIS K 6900).

[Film of the present invention]
The film of the present invention contains a mixed resin of a polylactic acid resin and a polyacetal resin as a main component.

<Polylactic acid resin>
The polylactic acid resin used in the present invention refers to a homopolymer of D-lactic acid or L-lactic acid, or a copolymer thereof. Specifically, a poly (D-lactic acid) whose structural unit is D-lactic acid. Lactic acid), poly (L-lactic acid) whose structural unit is L-lactic acid, poly (DL-lactic acid) which is a copolymer of L-lactic acid and D-lactic acid, and D-lactic acid and L-lactic acid. A mixed resin of a plurality of the above copolymers having different copolymerization ratios with lactic acid is also included.

  The copolymer of L-lactic acid and D-lactic acid has a copolymerization ratio of D-lactic acid and L-lactic acid (hereinafter referred to as “D / L ratio”) of D-lactic acid and L-lactic acid. It is important that the / L ratio is greater than 5/95, 15/85 or less, or 85/15 or more, and less than 95/5, greater than 5/95, 13/87 or less, or 87/13 or more, It is preferably less than 95/5, most preferably 6/94 or more and 10/90 or less, or 90/10 or more and 94/6 or less.

  When the copolymerization ratio of D-lactic acid is 5 or less or 95 or more, high crystallinity is exhibited, the melting point is high, and heat resistance and mechanical properties tend to be excellent. However, when the film of the present invention is used as a heat-shrinkable film, since it usually involves printing and a bag making process using a solvent, the crystallinity of the constituent material itself is improved in order to improve printability and solvent sealability. It needs to be lowered moderately. 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 as a film in which crystallization is suppressed by adjusting stretching conditions, crystallization proceeds before shrinkage due to heating during heat shrinkage, and as a result, there is a tendency to cause shrinkage unevenness and insufficient shrinkage. .

  On the other hand, when the copolymerization ratio of D-lactic acid is higher than 15 or less than 85, the crystallinity is almost completely lost, so that when the labels collide with each other after heat shrinkage, they are fused by heat. Troubles such as are likely 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 the problems described above. Become.

  In the present invention, it is also possible to blend polylactic acid resins having different D / L ratios. It is preferable to blend polylactic acid resins having different D / L ratios because the D / L ratio of the polylactic acid resins can be adjusted relatively easily. In this case, the average value of the D / L ratios of the 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, for example, when used in heat shrinkable film applications, heat resistance and heat A heat-shrinkable film having a balanced shrinkage characteristic can be obtained.

  Moreover, the said polylactic acid-type resin can contain a small amount of copolymerization component, if it is in the range which does not impair an essential property. Examples of the copolymer component include α-hydroxycarboxylic acids other than lactic acid, non-aliphatic dicarboxylic acids such as terephthalic acid, aliphatic dicarboxylic acids such as succinic acid, non-aliphatic diols such as ethylene oxide adducts of bisphenol A, ethylene glycol At least one selected from the group consisting of aliphatic diols such as For the purpose of increasing the molecular weight, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound, or an acid anhydride can be used.

  Examples of α-hydroxycarboxylic acid units other than lactic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, and 2-hydroxy-3- Examples thereof include bifunctional aliphatic hydroxycarboxylic acids such as methylbutyric acid, 2-methyllactic 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, suberic acid, sebacic acid, and dodecanedioic acid.

  The copolymerization ratio in the copolymer of lactic acid and α-hydroxycarboxylic acid other than lactic acid is not particularly limited, but the higher the proportion of lactic acid, the less the consumption of petroleum resources, and the more preferable the rigidity and transparency. The copolymerization ratio is preferably determined in consideration of a balance of physical properties such as impact resistance. Further, it is preferable to copolymerize at a ratio not exceeding the range of the Vicat softening point described later. Specifically, the copolymerization ratio of lactic acid and a copolymer of α-hydroxycarboxylic acid other than lactic acid, aliphatic diol, or aliphatic dicarboxylic acid is α-hydroxycarboxylic acid other than lactic acid / lactic acid, aliphatic diol, Or aliphatic dicarboxylic acid = 95/5 to 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. Moreover, as a structure of these copolymers, a random copolymer, a block copolymer, and a graft copolymer are mentioned, Any structure may be sufficient. However, a block copolymer or a graft copolymer is preferable from the viewpoint of impact resistance and transparency of the film.

  The weight (mass) average molecular weight of the polylactic acid-based resin is 20,000 or more, preferably 40,000 or more, more preferably 60,000 or more, and the upper limit is 400,000 or less, preferably 350,000 or less. More preferably, it is 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 the polymerization method of 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.

  Typical examples of the polylactic acid resin preferably used in the present invention include “Nature Works” manufactured by Nature Works LLC and the like. Specific examples of the random copolymer of PLA resin, diol, and dicarboxylic acid include, for example, “GS-Pla” (manufactured by Mitsubishi Chemical Corporation), and specific examples of the block copolymer include, for example, “Plamate” (manufactured by DIC) can be mentioned.

<Polyacetal resin>
The polyacetal resin used in the present invention is a polymer having an oxymethylene unit as a main repeating skeleton, and is composed of a polyacetal homopolymer obtained by polymerization using formaldehyde or trioxane as a main raw material, or mainly composed of oxymethylene units. It is a polyacetal copolymer containing 15% by mass or less of oxyalkylene units having 2 to 8 adjacent carbon atoms in the chain. Further, the polyacetal-based resin may be any of a block copolymer, a terpolymer, and a crosslinked polymer having other structural units. These polymers can be used alone or in admixture of two or more.

  Specific examples of other structural units include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane, 1,3. -Dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and the like can be mentioned.

  Among them, from the viewpoint of transparency when used in heat shrinkable film applications, the polyacetal resin is preferably a polyacetal copolymer, and the oxyalkylene having 2 to 8 adjacent carbon atoms in the main chain. More preferred are polyacetal copolymers containing 15% by mass or less of units, or polyacetal copolymers containing 10% by mass or less of oxyalkylene units having 2 to 8 adjacent carbon atoms in the main chain. Polyacetal copolymer containing 1% by mass or more and 10% by mass or less of oxyalkylene units having 1 adjacent carbon atom, or 1% by mass or more of oxyalkylene units having 2 to 4 adjacent carbon atoms in the main chain A polyacetal copolymer containing at most% by mass is particularly preferred.

  The method for producing the polyacetal resin in the present invention is not particularly limited, and can be produced by a known method. As an example of a typical method for producing a polyacetal homopolymer, high-purity formaldehyde is introduced into an organic solvent containing a basic polymerization catalyst such as an organic amine, an organic or inorganic tin compound, or a metal hydroxide. Examples of the method include polymerizing and filtering the polymer, followed by heating in acetic anhydride in the presence of sodium acetate to acetylate the polymer terminal.

  As a typical method for producing a polyacetal copolymer, a high purity trioxane and a copolymer component such as ethylene oxide and 1,3-dioxolane are introduced into an organic solvent such as cyclohexane, and a boron trifluoride diethyl ether complex is prepared. After the cationic polymerization using such a Lewis acid catalyst, a method of producing by deactivation of the catalyst and stabilization of the end groups, or trioxane, co-polymer into a self-cleaning stirrer without using any solvent. Examples thereof include a method in which a polymerization component and a catalyst are introduced and bulk polymerization is performed, and then an unstable terminal is further decomposed and removed.

  The viscosity of the polyacetal resin is not particularly limited as long as it can be used as a molding material, but the melt flow rate (MFR: JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1 g / 10. Min. Or more, preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, 30 g / 10 min or less, preferably 25 g / 10 min or less, more preferably 20 g / 10 min or less Are preferably used. If the MFR is 0.1 g / 10 min or more, the extrudability can be maintained satisfactorily. On the other hand, if the MFR is 30 g / 10 min or less, it is difficult to cause unevenness in film thickness and mechanical strength, which is preferable.

A typical example of a polyacetal homopolymer is “Tenac” manufactured by Asahi Kasei Chemicals Corporation. Representative products of polyacetal copolymer include “Aramis” manufactured by Toray Industries, “Duracon” manufactured by Polyplastics, and “Iupital” manufactured by Mitsubishi Engineering Plastics.

  When a polyacetal resin is left in a molten state in a molding machine for a long time, thermal decomposition occurs, which may lead to generation of formaldehyde gas, film discoloration, deterioration of physical properties, and the like. The thermal decomposition pattern of the polyacetal-based resin is a main chain cleavage type, which is a typical depolymerization type that is cleaved from the end of the main chain. Polyacetal resins are susceptible to thermal decomposition by acidic additives. Therefore, it is effective to contain an antioxidant as an acid catcher as a heat stabilizer in order to suppress thermal decomposition.

  Suitable antioxidants that can be contained in the polyacetal resin include hindered phenol compounds, phosphite compounds, thioether compounds, vitamin compounds, and the like.

  Specific product names of hindered phenol compounds include Adeka's “Adekastab”, Ciba Japan's “Irganox”, Sumitomo Chemical's “Smilizer”, and Cyanamid's “Sianox”. .

  Specific product names of phosphite compounds include Adeka's “Adekastab”, Ciba Japan's “Irgafos”, Sumitomo Chemical's “Smilizer”, Clariant's “Sandstub”, GE's “West” And so on.

  Specific product names of thioether compounds include “Adekastab” manufactured by Adeka, “Irganox” manufactured by Ciba Japan, “Sumizer” manufactured by Sumitomo Chemical Co., “Seanox” manufactured by Cypro Kasei Co., Ltd., and the like.

  Specific product names of vitamin-based antioxidants include “Tocopherol” manufactured by Eisai and “Irganox” manufactured by Ciba Japan.

<Mass ratio of polylactic acid resin and polyacetal resin>
In the present invention, it is important that the mass ratio of the polylactic acid resin and the polyacetal resin is in the range of 95/5 to 60/40. The mass ratio is preferably 90/10 or more and 70/30 or less, and more preferably 90/10 or more and 75/25 or less. By setting the mass ratio of the polyacetal resin to the polylactic acid resin to be 5 or more, it is possible to expect a fracture resistance effect and an effect of maintaining transparency after immersion in hot water. On the other hand, by setting the mass ratio of the polyacetal resin to the polylactic acid resin to 40 or less, it is possible to maintain transparency during film formation when used as a heat-shrinkable film.

  The film of the present invention includes a polylactic acid-based resin and a polyacetal-based resin in the above mass ratio, so that when the film is used as a heat-shrinkable film as well as the film itself, it is heat-shrinkable in a warm water atmosphere. It is possible to suppress a decrease in transparency when the film is attached to the adherend. Under a warm water atmosphere (that is, high humidity and high temperature range higher than the glass transition temperature of the polylactic acid resin), the warm water is immersed in the polylactic acid resin. When this is returned to a normal temperature atmosphere (temperature range below the glass transition temperature of the polylactic acid resin), the water immersed in the polylactic acid resin dries, and the water content becomes voids in the polylactic acid resin. Exists. The presence of the voids causes a light scattering phenomenon due to a difference in refractive index between the polylactic acid resin and the voids, which causes a decrease in transparency.

  On the other hand, when a polyacetal resin is contained in the polylactic acid resin, the polyacetal resin acts as a crystal nucleating agent for the polylactic acid resin, and improves the crystallinity of the mixed resin. As a result, the polylactic acid resin The intrusion of warm water inside can be suppressed. Therefore, when a mixed resin of a polylactic acid resin and a polyacetal resin is used, it is possible to suppress a decrease in transparency after immersion in warm water. Further, this effect can be further enhanced by inducing oriented crystallization by stretching the mixed resin. Therefore, in the case of the film of the present invention, when the label is attached to the adherend as a heat-shrinkable film and contracted in a warm water atmosphere, the decrease in transparency before and after the treatment is reduced, and the design of the adherend is reduced. Can increase the sex.

<Lubricant>
The film of the present invention can contain a lubricant. In the film of the present invention, the lubricant imparts unevenness to the film surface, thereby suppressing blocking between the films and improving the handleability of the film. By imparting appropriate irregularities to the film surface, it becomes possible to reduce the coefficient of friction between films while maintaining the transparency of the film, so the roll winding process, slit process, printing process during film formation In a heat shrink film having various processes such as a bag making process and an attaching process to an adherend, it becomes a very important factor.

  As the lubricant used in the present invention, amorphous silica, agglomerated silica, colloidal silica, alumina silicate, crosslinked poly (meth) acrylate ester particles, crosslinked polystyrene particles, calcium carbonate and the like are preferably used, and particularly preferably amorphous. Silica, alumina silicate, and crosslinked polymethyl methacrylate. In addition to the above, the lubricant shown above may be used as long as the object of the present invention is not impaired.

  The lubricant used in the present invention is 0.01% by mass or more, preferably 0.03% by mass or more, and more preferably 0.06% by mass or more based on the total amount of the polylactic acid resin and the polyacetal resin. 0.2 mass% or less, preferably 0.18 mass% or less, more preferably 0.16 mass% or less. When the content of the lubricant is 0.01% by mass or more, irregularities can be formed on the film surface, and the slipperiness of the film can be expressed. Moreover, if the content rate of a lubricant is 0.2 mass% or less, a lubricant does not disperse | distribute but it can prevent the appearance defect by the surface roughness and inhibition of transparency.

  Furthermore, the film of this invention can further contain 1 type, or 2 or more types of other thermoplastic resins in the said mixed resin in the range which does not inhibit the effect of this invention remarkably. Examples of such thermoplastic resins include polyethylene resins, polypropylene resins, polyamide resins, polystyrene resins (GPPS (general purpose polystyrene)), HIPS (impact polystyrene), and SBS (styrene-butadiene copolymer). , SIS (styrene-isoprene copolymer), SEBS (styrene-ethylene-butylene-styrene copolymer), SEPS (styrene-ethylene-propylene-styrene copolymer), styrene-carboxylic acid copolymer) and the like. Can do.

  Furthermore, the film of the present invention is obtained by adding a soft resin to the above mixed resin for the purpose of improving impact resistance, transparency, molding processability and various characteristics of the film as long as the effects of the present invention are not significantly impaired. May be.

  Examples of the soft resin include aliphatic polyester resins excluding polylactic acid resins, aromatic aliphatic polyester resins, copolymers of diol, dicarboxylic acid, and lactic acid resins, and core-shell structure rubbers.

  Among the above-mentioned soft resins, aliphatic polyester resins excluding polylactic acid resins are preferable. The aliphatic polyester resin excluding the polylactic acid resin is an aliphatic polyester mainly composed of an aliphatic dicarboxylic acid or a derivative thereof and an aliphatic polyhydric alcohol. Examples of the aliphatic dicarboxylic acid residue constituting the aliphatic polyester resin include residues derived from succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Examples of the aliphatic polyhydric alcohol residue include aliphatic diol residues derived from ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like.

  The aliphatic dicarboxylic acid residue preferably used in the present invention is a succinic acid residue or an adipic acid residue, and the aliphatic polyhydric alcohol residue is a 1,4-butanediol residue.

  Furthermore, the aliphatic polyester resin suitably used in the film of the present invention preferably has a melting point of 100 ° C. or higher and 170 ° C. or lower. Even in the range of 60 ° C. to 100 ° C. in which normal shrinkage is performed by adjusting the melting point to that range, the aliphatic polyester resin can maintain a crystalline state, and as a result, plays a role like a column during shrinkage. By carrying it, it becomes possible to obtain even better shrinkage finish.

  The content of the aliphatic polyester resin is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and 30% by mass or less, preferably 25% by mass or less, more preferably 20%. It is below mass%.

  In addition, examples of the core-shell structure rubber preferably used in the present invention include silicone acrylic composite rubber. As a specific example, the core part is made of a copolymer of a siloxane compound and a (meth) acrylic monomer, and the shell part is made of a homopolymer or copolymer of a (meth) acrylic monomer. Is mentioned. Examples of the siloxane compound include dimethylsiloxane. Moreover, as a (meth) acrylic-type monomer used for a core part, butyl (meth) acrylate, 2-ethylhexyl acrylate, etc. are mentioned. Furthermore, examples of the (meth) acrylic monomer used for the shell part include methyl (meth) acrylate.

  The content of the core-shell structured rubber is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and 30% by mass or less, preferably 25% with respect to the total amount of the resin constituting the film. It is not more than mass%, more preferably not more than 20 mass%.

  In the film of the present invention, for the purpose of improving various properties of the impact resistance, transparency, molding processability and heat shrinkable film, a plasticizer may be further added within a range that does not significantly impair the effects of the present invention. . Examples of the plasticizer include fatty acid ester plasticizers, phthalate ester plasticizers, trimellitic ester plasticizers, and the like.

  Specific examples of the fatty acid ester plasticizer include dibutyl adipate, diisobutyl adipate, diisononyl adipate, diisodecyl adipate, di (2-ethylhexyl) adipate, di (n-octyl) adipate, di (n-decyl) adipate, dibutyldipropyl Examples include glycol adipate, dibutyl sebacate, di (2-ethylhexyl) sebacate, di (n-hexyl) azelate, di (2-ethylhexyl) azelate, di (2-ethylhexyl) dodecanedionate and the like.

  Specific examples of the phthalate ester plasticizer include diisononyl phthalate, diisodecyl phthalate, and di (2-ethylhexyl) phthalate. Further, specific examples of the trimellitic acid ester plasticizer include tri (2-ethylhexyl) trimellitate.

  In the film of the present invention, it is important that the coefficient of static friction according to JISK7125 is 0.1 or more and 0.55 or less, and more preferably 0.15 or more and 0.50 or less. More preferably, it is 0.2 or more and 0.45 or less.

  The coefficient of friction is an index for determining adaptability to the printing process and the mounting process on the covering. Currently, in gravure printing, which is a general printing method in a printing process, printing is performed via many rolls. Moreover, in the attachment process to a covering body, the roll film which became bag shape is cut | judged, a bag-like heat-shrinkable film is opened, and attachment to a covering body is performed. Therefore, when the static friction coefficient of the film is 0.5 or more, when the film passes through the roll in the printing process, color misalignment of printing or folding of the film itself is likely to occur due to friction between the film and the roll. In addition, even when the bag-like film is opened in the mounting process, the film cannot be opened successfully due to friction between the films, which may cause a problem in mounting on the covering. On the other hand, when the coefficient of static friction of the film is 0.1 or less, the film slips on the roll when the film is wound on the roll or when the wound roll is unwound, and the film is likely to be unwound. Is likely to occur.

[The stretched film and heat-shrinkable film of the present invention]
The film of the present invention can be made into a stretched film or a heat-shrinkable film by stretching in at least one direction. By stretching the film of the present invention, the tensile strength and impact strength can be increased. Moreover, it can also be used as a heat-shrinkable film by adjusting the heat setting temperature after stretching. In the case of a stretched film, a biaxially stretched film is also included in addition to a uniaxially stretched film.

  When the film of the present invention is used as a heat shrinkable film, it is important that the heat shrinkage rate in the main shrinkage direction when immersed in warm water at 80 ° C. for 10 seconds is 20% or more, more preferably 30%. That's it.

  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. At present, the shrinkage processing machine most commonly used industrially for labeling of PET bottles is generally called a steam shrinker that uses steam as a heating medium for shrinking. Furthermore, the heat-shrinkable film needs to be sufficiently heat-shrinked at a temperature as low as possible from the viewpoint of the influence of heat on the object to be coated. However, in the case of a film with high temperature dependence and extremely different shrinkage ratios depending on the temperature, parts with different shrinkage behavior tend to occur with respect to the temperature spots in the steam shrinker, so shrinkage spots, wrinkles, avatars, etc. occur. However, the shrink-finished appearance tends to deteriorate. From the viewpoint of including these industrial productivity, if the thermal shrinkage rate in the main shrinkage direction of the film when immersed in warm water at 80 ° C. for 10 seconds is 20% or more, the film is sufficiently adhered to the coated object within the shrinkage processing time. It is preferable because it can produce a good shrink-finished appearance without spots, wrinkles and avatars. From this, the film of the present invention preferably has a heat shrinkage at 80 ° C. of 20% or more and 70% or less.

  The “main shrinkage direction” means the larger one of the longitudinal direction and the transverse direction in the stretching direction. For example, when attached to a bottle, it is a direction corresponding to the outer circumferential direction.

  The heat shrinkage rate in the direction perpendicular to the main shrinkage direction of the heat shrinkable film of the present invention is preferably 10% or less, preferably 5% or less when immersed in hot water at 80 ° C. for 10 seconds. Is more preferable, and it is further more preferable that it is 3% or less. 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.

  In addition, although the upper limit of said heat shrinkage is not described, since heat shrinkage does not become shorter than the length of the film before extending | stretching, the upper limit of heat shrinkage is a shrinkage rate used as the film length before extending | stretching. .

   Regarding the transparency of the heat-shrinkable film of the present invention, when a film having a thickness of 50 μm is measured according to JIS K7105, the total haze value is preferably 8% or less, more preferably 7% or less, and 6%. More preferably, it is more preferably 5% or less. If total haze value is 8% or less, the visibility of the covering body which mounted | wore the film can be improved.

  In addition, the transparency of the heat-shrinkable film of the present invention after immersion in hot water is such that two ends of a rectangular metal frame 130 mm long, 170 mm wide and 5 mm wide as shown in FIG. When the haze value is measured by measuring the film after being immersed in warm water of 80 ° C. for 20 minutes in a state in accordance with JIS K7105, the total haze value is preferably 15% or less, and 13% or less. It is more preferable that it is 10% or less. If the total haze value of the film after the immersion in warm water is 15% or less, dullness of the printed pattern when the film is attached to the covering by steam shrinker or the like can be suppressed.

<The manufacturing method of the film of this invention, a stretched film, and a heat-shrinkable film>
The film, stretched film, and heat-shrinkable film of the present invention can be produced by a known method using the mixed resin. The form of the film may be either flat or tube-like, but the flat form is preferable in terms of productivity (a few products can be taken in the width direction of the original film) and printing on the inner surface. .

  As a method for producing a flat film, for example, a resin is melted by using a plurality of extruders, co-extruded from a T die, solidified by cooling with a chilled roll, roll-stretched in the vertical direction, and tenter-stretched in the horizontal direction. In the case of printing, annealing, cooling, and printing, a corona discharge treatment is performed on the surface, and the film is obtained by 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 such as heat-shrinkable labels that shrink mainly in one direction, 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 perpendicular thereto is 1 or more and 2 or less (1 time indicates that the film is not stretched), preferably 1.01 or more and 1.5 or less, and substantially uniaxially stretched. It is desirable to select a magnification ratio in the category of. 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.

  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, stretched film, and heat-shrinkable film of the present invention may be a single layer, and has surface functional properties such as slipperiness, heat resistance, solvent resistance, and easy adhesion on the film surface. For the purpose of imparting, imparting further fracture resistance, and imparting further shrinkage finish, a laminated structure in which other layers are stacked may be used. That is, when the mixed resin layer of the polylactic acid-based resin and the polyacetal-based resin is the (I) layer, these mixed resin layers and layers (II) and (III) layers having different compositions or additives were laminated, (I) / (II) / (I), (I) / (II) / (III), (II) / (I) / (II), (II) / (I) / (III), (II ) / (I) / (III) / (II). In this case, the lamination ratio of each layer can be appropriately adjusted according to the application and purpose.

  Examples of the method for forming the laminate include a co-extrusion method, a method of forming a film of each layer, and then superposing and heat-sealing, a method of bonding with an adhesive, and the like.

  The total thickness of the film, stretched film, and heat-shrinkable film of the present invention is not particularly limited, whether it is a single layer or a laminated layer. However, the transparency, shrinkage processability, raw material cost, etc. From the viewpoint, the thinner one is preferable. Specifically, the total thickness of the film before stretching is 500 μm or less, preferably 400 μm or less, more preferably 250 μm or less, and the total thickness of the film after stretching is preferably 80 μm or less, preferably 70 μm or less, More preferably, it is 50 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.

<Molded products, heat-shrinkable labels, containers>
The film, stretched film, and heat-shrinkable film of the present invention can be processed from a flat shape into a cylindrical shape or the like by a packaged article and used for packaging. When printing is required in a cylindrical container such as a plastic bottle, first print the required image on one side of a wide flat film wound up on a roll, and then cut it to the required width while the print side is inside. The center seal (the shape of the seal portion is a so-called envelope) may be folded into a cylindrical shape. As the center sealing method, an organic solvent bonding method, a heat sealing method, an adhesive method, and an impulse sealer method can be considered. Among these, from the viewpoint of productivity and appearance, an adhesion method using an organic solvent is preferably used.

  In addition, the film of the present invention, stretched film, heat shrinkable film is excellent in heat shrink characteristics, shrink finish, transparency, slipperiness, etc. of the film. It can be used as various molded products such as bottles (blow bottles), trays, lunch boxes, prepared food containers, dairy products containers, etc., by stacking printed layers, vapor deposition layers, and other functional layers as necessary. .

  Furthermore, when the film, stretched film, and heat-shrinkable film of the present invention are used as a heat-shrinkable label for food containers (for example, soft drinks or PET bottles, glass bottles, preferably PET bottles for foods), it is complicated. A container with a beautiful label without wrinkles, avatars, etc. that can be in close contact with the shape even if it has a shape (for example, a cylinder with a narrow center, a square column with a corner, a pentagonal column, a hexagonal column, etc.) can get. The molded article and container of this invention can be produced by using a normal molding method.

  Especially when the film of the present invention is used for heat-shrinkable film applications, it has excellent low-temperature shrinkage and shrinkage finishing properties. , Materials having extremely different coefficients of thermal expansion and water absorption from the heat-shrinkable film of the present invention, such as polyolefin resins such as metals, porcelain, glass, paper, polyethylene, polypropylene, polybutene, polymethacrylate resins, polycarbonate It can be suitably used as a heat-shrinkable label material for a plastic package (container) using at least one selected from polyester resins such as polyethylene resins, polyethylene terephthalates, polybutylene terephthalates, and polyamide resins as constituent materials.

  As the material constituting the plastic package, in addition to the above resins, polystyrene, rubber-modified impact-resistant polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer Polymer, acrylonitrile-butadiene-styrene copolymer (ABS), (meth) acrylic acid-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, phenol resin, urea resin, melamine resin, epoxy resin, A saturated 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 film, heat-shrinkable film, heat-shrinkable label, and container equipped with the label of the present invention will be described below with reference to examples.

    In addition, the measured value and evaluation which are shown to an Example were performed as follows. In the examples, the film take-up (flow) direction is described as MD (vertical direction), and the perpendicular direction thereof is described as TD (transverse direction).

<Measurement method>
(1) Evaluation of shrinkage finish Heat-shrinkable film with a grid of 10 mm intervals was cut with an oil-based pen into a size of MD160 mm × TD235 mm, both ends of TD were overlapped by 7 mm, and heat-sealed with a heat sealer, and cylindrical A film was prepared. The cylindrical film is attached to a cylindrical plastic bottle having a capacity of 500 mL, and is passed through the shrinking tunnel having a length of 3.2 m (3 zones) of the steam heating method for about 5 seconds without rotating. Coated. The atmospheric temperature in the tunnel in each zone was set to a range of 70 to 90 ° C. by adjusting the amount of steam with a steam valve.
A: Shrinkage is sufficient and no lattice distortion occurs.
○: Shrinkage is sufficient and distortion of the lattice is slightly caused, but there is no practical problem.
X: Shrinkage is sufficient, but distortion of the lattice is remarkably generated.

(2) Thermal contraction rate
The obtained heat-shrinkable film was cut into a size of MD 100 mm × TD 100 mm, immersed in a hot water bath at 80 ° C. for 10 seconds, and the amount of shrinkage was measured. As for the thermal shrinkage rate, the ratio of shrinkage to the original size before shrinkage was expressed as a% value for MD and TD.

(3) Static friction coefficient In order to evaluate the slipperiness of the obtained film, the static friction coefficient was measured according to JIS K7125 and evaluated according to the following criteria. Evaluation was based on the average value of three measurements.

(4) Haze value
In order to evaluate the transparency of the obtained film, the haze value was measured according to JIS K7105 and evaluated according to the following criteria.
A: Haze value is 4% or less.
○: The haze value exceeds 4% and is 8% or less.
X: Haze value exceeds 8%.

(5) Haze value after immersion in warm water In order to evaluate the visibility when the obtained film is mounted on a covering, two rectangular metal frames 130 mm long, 170 mm wide and 5 mm wide as shown in FIG. The film was immersed in warm water at 80 ° C. for 20 minutes with both ends of the film in the main shrink direction sandwiched, and then the haze value was measured according to JIS K7105 and evaluated according to the following criteria.
A: Haze value is 10% or less.
○: Haze value exceeds 10% and is 15% or less.
X: Haze value exceeds 15%.

Moreover, the raw material used by each Example and the comparative example is as follows.
(Polylactic acid resin)
-Polylactic acid resin 1 ... manufactured by Nature Works LLC, trade name: NatureWorks 4032D, L-form / D-form weight = 98.8 / 1.2, hereinafter abbreviated as "PLA1 (NW4032)".
-Polylactic acid resin 2 ... manufactured by Nature Works LLC, trade name: NatureWorks 4060D, L-form / D-form weight = 88/12, hereinafter abbreviated as "PLA2 (NW4060)".
-Polylactic acid resin 3 ... manufactured by Nature Works LLC, trade name: NatureWorks 4042D, L-form / D-form quantity = 95.75 / 4.25, hereinafter abbreviated as "PLA3 (NW4042)".

(Polyacetal resin)
Polyacetal resin 1: manufactured by Mitsubishi Engineering Plastics, trade name: Iupital F20-01, hereinafter abbreviated as “POM1 (F20-01)”.
Polyacetal resin 2: manufactured by Mitsubishi Engineering Plastics, trade name: Iupital V20-HT, hereinafter abbreviated as “POM2 (V20-HT)”.

(Heat stabilizer)
Heat stabilizer: manufactured by Ciba Japan, trade name: Irganox 1010 (hindered phenol antioxidant), hereinafter abbreviated as “IRGANOX 1010”.

(Lubricant)
-Lubricant: manufactured by Nippon Shokubai Co., Ltd., trade name: Seahoster KE-P250 (amorphous silica, average particle size 2.25 to 2.75 μm), hereinafter abbreviated as “KE-P250”.

(Examples 1 and 2, Reference Example 1)
Polylactic acid-based resin 1 and polylactic acid-based resin 2 shown in Table 1, polyacetal-based resin 1, 98 parts by mass of polylactic acid-based resin 1 and 2 parts by mass of a lubricant are mixed in advance, and set temperature with a twin-screw extruder. A mixed resin composed of melt-mixed and pelletized at 200 ° C. (hereinafter referred to as “lubricant A”) is charged into a twin-screw extruder (manufactured by Mitsubishi Heavy Industries, Ltd.), melt-mixed at a set temperature of 190 ° C., After extruding from a base having a set temperature of 190 ° C., it was taken up by a cast roll at 50 ° C. and cooled and solidified to obtain an unstretched film having a width of 200 mm and a thickness of 200 μm. Next, the film was stretched by a film tenter (manufactured by Kyoto Kikai Co., Ltd.) under the stretching conditions of 70 ° C. and 4 times in the lateral direction to obtain a heat shrinkable film. Table 1 shows the shrinkage finish evaluation of the obtained film.

(Examples 3 to 7, Comparative Examples 1 and 2)
A mixed resin composed of the polylactic acid resin 1 or 2 shown in Table 2, the polyacetal resin 1 or 2, the thermal stabilizer “IRGANOX1010”, and the lubricant A is put into a twin screw extruder (Mitsubishi Heavy Industries, Ltd.). The mixture was melt-mixed at a preset temperature of 190 ° C., extruded from a die at a preset temperature of 190 ° C., taken up by a cast roll at 50 ° C., and cooled and solidified to obtain an unstretched film having a width of 200 mm and a thickness of 200 μm. Next, the film was stretched by a film tenter (manufactured by Kyoto Kikai Co., Ltd.) at 65 ° C. under a stretching condition of 4 times in the transverse direction, and then heat treated at 85 ° C. in the tenter to adjust the heat shrinkage rate of the film. Got. Table 2 shows the evaluation of the obtained film.

(Examples 8 and 9, Comparative Examples 3 and 4)
Polylactic acid-based resin 2 or 3 shown in Table 3, polyacetal-based resin 1, heat stabilizer and lubricant A mixed resin or polylactic acid-based resin 2 or 3, polyacetal-based resin 1 and heat stability The mixed resin composed of the agent was extruded under the same conditions as in Example 3 to obtain an unstretched film having a width of 200 mm and a thickness of 250 μm. These unstretched films were stretched by a film tenter (manufactured by Kyoto Kikai Co., Ltd.) under stretching conditions of 75 ° C. and 5 times in the lateral direction, and then heat treated at 95 ° C. in the tenter to adjust the heat shrinkage rate of the film. A heat-shrinkable film was obtained. Table 3 shows the evaluation of the obtained film.

(Examples 10 and 11, Comparative Example 5)
The unstretched films obtained in Examples 8 and 9 were stretched with a film tenter (manufactured by Kyoto Kikai Co., Ltd.) under stretching conditions of 75 ° C. and 5 times in the lateral direction to obtain heat-shrinkable films. On the other hand, a polylactic acid unstretched film having a width of 200 mm and a thickness of 250 μm was prepared in the same manner as in Examples 8 and 9 using a mixed resin composed of the polylactic acid resin 2 or 3 shown in Table 4, a heat stabilizer, and a lubricant A. Got. This polylactic acid unstretched film was stretched with a film tenter under stretching conditions of 75 ° C. and 5 times in the transverse direction to obtain a heat-shrinkable film. The obtained film was cut into a size of MD 150 mm × TD 200 mm, and immersed in warm water at 80 ° C. for 20 minutes with two rectangular metal frames sandwiching both ends of the film in the main contraction direction. Table 4 shows the evaluation of the obtained film.

        As shown in Table 1, the heat-shrinkable film of the present invention (Examples 1 and 2) is considered to have a good shrinkage finish with little shrinkage unevenness during heat shrinkage. On the other hand, as shown in Table 1, a film (Reference Example 1) in which the D / L ratio of D-lactic acid and L-lactic acid of the polylactic acid-based resin exceeds the range defined by the present invention is described in the film. The distortion of the lattice was remarkably generated, and the shrinkage unevenness considered to be derived from the crystallization of the resin composition occurred. Moreover, as shown in Table 2, it turns out that the heat-shrinkable film (Examples 3-7) of this invention has sufficient heat-shrinkable expression and favorable transparency. On the other hand, as shown in Table 2, in the film (Comparative Examples 1 and 2) in which the weight ratio of the polylactic acid-based resin to the polyacetal-based resin exceeds the range defined by the present invention, the processability as a heat-shrinkable film or It is difficult to maintain transparency. In addition, as shown in Table 3, by adding an appropriate number of appropriate lubricants, the quality of the heat-shrinkable film is further improved in order to improve the slipperiness of the film without hindering physical properties such as transparency. There is an effect of improving (see Examples 8 and 9, Comparative Examples 3 and 4). Furthermore, as shown in Table 4, by using a polyacetal resin in the range specified by the present invention for the polylactic acid resin, it is possible to suppress deterioration of transparency after immersion in hot water, and the heat shrinkability of the present invention. Even after the film is attached to the clothing body, the design can be sufficiently exhibited (Examples 10 and 11). On the other hand, as shown in Table 4, the polylactic acid resin alone deteriorated the transparency after immersion in warm water (Comparative Example 5).

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the present invention can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and it is understood that a film accompanying such a change is also included in the technical scope of the present invention. It must be.

    The present invention is a film excellent in transparency, heat shrinkability at the time of label mounting, and transparency after mounting, not only unstretched film, but also stretched film, heat shrinkable film, etc. And used as shrinkage labels.

DESCRIPTION OF SYMBOLS 1 Heat-shrinkable film of this invention 2 Rectangular metal frame 3 Fixing tool

Claims (7)

The mixed resin of polylactic acid resin and polyacetal resin containing as a main component, wherein the polylactic acid mass ratio between the resin and the polyacetal resin is at least one of Der Ru full Irumu 95/5 or 60/40 or less A heat-shrinkable film characterized by having a heat shrinkage rate of 20% or more in the main shrinkage direction when stretched in the direction and immersed in warm water at 80 ° C. for 10 seconds. The polylactic acid resin is a copolymer of D-lactic acid and L-lactic acid, and the D / L ratio of D-lactic acid and L-lactic acid is greater than 5/95, 15/85 or less, or 85/15 or more. The heat-shrinkable film according to claim 1, smaller than 95/5. The mixed resin contains a lubricant, and the content of the lubricant is 0.01 wt% or more and 0.2 wt% or less with respect to the total amount of the polylactic acid resin, the polyacetal resin and the lubricant, and the film The heat-shrinkable film according to claim 1, wherein the coefficient of static friction is from 0.1 to 0.5. Hot water at 80 ° C. with a haze value in accordance with JIS K7105 of 8% or less and with both ends of the film in the main shrinking direction sandwiched between two rectangular metal frames 130 mm long, 170 mm wide and 5 mm wide The heat-shrinkable film according to any one of claims 1 to 3, wherein a haze value based on JIS K7105 after being immersed for 20 minutes is 15% or less. A molded product using the heat-shrinkable film according to claim 1 as a base material. A heat-shrinkable label using the heat-shrinkable film according to claim 1 as a base material. The heat-shrinkable label according to moldings or claim 6 of claim 5 is attached, the container.

Images