JP2012188548A - Food packaging film - Google Patents

Abstract

The present invention provides a new food packaging film which has low elution, film unwinding properties and excellent appearance.
A component A mainly composed of a chlorine-containing resin, a component B mainly composed of a chlorine-free resin having a mass average molecular weight (Mw) of 50,000 to 400,000, and a resin composition X containing a lubricant. Is a film for food packaging, wherein the mass ratio of the content of the following component A and the following component B in the resin composition X is in the range of 99: 1 to 55:45, and the following component A and The content of the lubricant is from 0.1 parts by mass to 5 parts by mass with respect to 100 parts by mass of the total content of the following component B, the temperature of the resin composition X is 190 ° C., and the wall shear stress is 1 × 10 ⁵ Pa. The film for food packaging in which the sliding speed in the range of 0.1 mm / sec or more and 10 mm / sec or less is provided.
[Selection figure] None

Description

  The present invention relates to a film for food packaging, which uses a chlorine-containing resin containing chlorine as one of main ingredients.

  Stretch films excellent in transparency, flexibility, and heat sealability are widely used as food packaging films for food packaging, particularly for fresh foods such as meat, fresh fish, and fruits and vegetables. Conventionally, as this type of film, a polyvinyl chloride resin composition in which an adipic acid ester plasticizer and various antifogging agents are blended with a polyvinyl chloride resin is generally formed into a film.

As for additives to be added to food packaging films, importance is placed on hygiene and transferability to foods.
The hygiene of additives is stipulated in the US FDA standards (Food and Drug Administration) and Japanese PL standards (voluntary regulations regarding vinyl chloride resin packaging containers and packaging), etc. Is established. On the other hand, with regard to transferability to foods and the like, an extraction test is defined as an evaporation residue test method by the Ministry of Health and Welfare Notification No. 20 test in 1982.
Under such circumstances, various additives have been used so far as additives to be added to food packaging films. However, with regard to additives, particularly plasticizers added to soften the film, the n-heptane extraction amount specified in the Ministry of Health and Welfare Notification No. 20 may be close to or exceed 150 ppm by mass. There was a case.

Therefore, the following proposals have been made regarding food packaging films.
For example, in Patent Document 1, an aliphatic polybasic acid polyester having a molecular weight of 1,000 to 3,000 as a plasticizer and a glycerin ester are used in combination with a polyvinyl chloride resin as a plasticizer. By using a polyester plasticizer as a composition containing 5 to 40 parts by weight of the polyester plasticizer and 40 to 1 parts by weight of glycerin ester, that is, by using a high molecular weight plasticizer, A vinyl chloride resin composition for food packaging that is extremely safe with little extraction of additives such as plasticizers, stabilizers, antifogging agents, etc. The proposal is made.

  However, since the composition has a high melt viscosity and low slipperiness, there has been a problem of film burning and a decrease in extrusion life due to an increase in the resin temperature. Furthermore, when there are many polyester plasticizers, the slipperiness of the film surface is reduced, and there is a problem that blurring occurs at the corners of the tray when packaging with an automatic packaging machine or the like, resulting in poor finish. In addition, when there are many glycerin ester plasticizers, the melt viscosity can be reduced and the extrusion can be stably performed due to the effect of imparting slipperiness, and the packaging suitability is excellent, but there is a problem that the amount of n-heptane extraction increases. there were.

Therefore, even when a polyester plasticizer is used, higher fatty acids having 8 to 22 carbon atoms are added to 100 parts by weight of the polyvinyl chloride resin so that the slipperiness and antifogging property of the film do not deteriorate. It has been proposed to add 0.1 to 1 part by weight (for example, see Patent Document 2).
However, the addition of higher fatty acids can compensate for the decrease in slipperiness, but the higher fatty acids themselves are hydrophobic and therefore the antifogging property is reduced, and water droplets are generated on the film surface, making it difficult to confirm the contents. This causes a new quality defect.

  8 to 22 parts by weight of an adipic acid polyester plasticizer having an average molecular weight of 1,000 to 3,000, 100 parts by weight of a polyvinyl chloride resin, an adipate ester plasticizer having an alkyl group having 8 or more carbon atoms, and / Or 8-22 parts by weight of a mixed adipic acid ester plasticizer obtained by reaction of two or more aliphatic alcohols having an alkyl group with 10 or less carbon atoms and adipic acid, 5-20 parts by weight of epoxidized vegetable oil, higher grade A polyvinyl chloride stretch film composed of 0.05 to 3 parts of an ester with a fatty acid and glycerin has been proposed (for example, see Patent Document 3).

  In this stretch film, a low-elution film suitable for food container packaging, which further reduces the amount of n-heptane extraction and has improved film unwinding power and film appearance, which are other film properties, is desired.

JP-A-2-269145 JP-A-9-176424 JP 2006-104242 A

  As described above, regarding food packaging films, particularly food packaging films made mainly of chlorine-containing resins, it is difficult to simultaneously satisfy the elution properties, unwinding properties and appearance (unevenness) required for food packaging applications. I had a problem.

  Therefore, the present invention does not provide a new food packaging film that has excellent plasticizer elution, film unwinding properties, and appearance (unevenness) in food packaging films that use chlorine-containing resins as one of the main ingredients. It is what.

The present invention is a food packaging film formed by molding a resin composition X containing the following component A, the following component B, and a lubricant, and the following component A and the following component B in the resin composition X The mass ratio of the content of the lubricant is in the range of 99: 1 to 55:45, and the content of the lubricant is 0.1 parts by mass or more and 5 parts by mass with respect to 100 parts by mass of the total content of the following component A and the following component B. A food product characterized in that the sliding speed at a temperature of 190 ° C. and a wall shear stress of 1 × 10 ⁵ Pa of the resin composition X is within a range of 0.1 mm / sec to 10 mm / sec. Propose packaging film.
Component A: Component mainly composed of chlorine-containing resin Component B: Component mainly composed of chlorine-free resin having a mass average molecular weight (Mw) of 50,000 to 400,000

  The present invention can suppress bleeding and elution of component B by blending component B mainly composed of chlorine-free resin having a relatively high molecular weight with component A mainly composed of chlorine-containing resin. Furthermore, by controlling the sliding speed of the resin composition X within a specific range, it is possible to impart a slipperiness suitable for a food packaging film, and the film unwinding property and the appearance of the film, particularly uniform and uniform. The property can be further improved. Therefore, the film for food packaging of the present invention can be suitably used as a wrap film for food packaging.

  Hereinafter, a film for food packaging (hereinafter referred to as “the present film”) as an example of an embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

<This film>
The present film can be obtained by molding a resin composition X containing a predetermined component A, a predetermined component B, and a lubricant in a predetermined ratio.

(Component A)
Component A in the present film is a component mainly composed of a chlorine-containing resin (hereinafter also referred to as “component A resin”).
Here, the component mainly composed of a chlorine-containing resin means that the component A contains a component other than the chlorine-containing resin, and the proportion of the chlorine-containing resin in the component A exceeds 50% by mass. This is a concept including 70% by mass or more, more preferably 90% by mass or more, and 100% by mass.

  Examples of the chlorine-containing resin include vinyl chloride resin, vinylidene chloride homopolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-ethylene vinyl acetate copolymer resin, vinyl chloride-ethylene copolymer resin, vinyl chloride-propylene copolymer. Resin, vinyl chloride-styrene copolymer resin, vinyl chloride-isobutylene copolymer resin, vinyl chloride-vinylidene chloride copolymer resin, vinyl chloride-urethane copolymer resin, vinyl chloride-acrylate copolymer resin, vinyl chloride-styrene- Maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitrile copolymer resin, vinyl chloride-butadiene copolymer resin, vinyl chloride-isoprene copolymer resin, vinyl chloride-chlorinated propylene copolymer resin, vinyl chloride-vinylidene chloride -Vinyl acetate copolymer resin, vinyl chloride Mention may be made of vinyl chloride copolymer resins such as maleic acid ester copolymer resins, vinyl chloride-methacrylic ester copolymer resins, vinyl chloride-acrylonitrile copolymer resins, vinyl chloride-maleimide copolymer resins, one of these A seed can be used alone, or two or more kinds can be used in combination.

  Further, the above-exemplified chlorine-containing resin and a co-polymer of α-olefin polymer resin such as polyethylene, polypropylene, polybutene, poly-3-methylbutene, or polyolefin such as ethylene-vinyl acetate copolymer resin, ethylene-propylene copolymer resin. Polymeric resin or chlorine-containing resin exemplified above, at least one selected from the group consisting of, for example, polystyrene, acrylic resin, polyurethane and styrene, and other monomeric resins (for example, maleic anhydride, butadiene, acrylonitrile, etc.) Copolymer resins and the like can also be used.

Furthermore, post-chlorinated vinyl chloride resins can also be used as component A resins.
Thereafter, the chlorinated vinyl chloride resin preferably has an average degree of polymerization of 500 to 1400 of the vinyl chloride resin before chlorination. If the average degree of polymerization is 500 or more, impact resistance can be maintained, and if the average degree of polymerization is 1400 or less, melt fluidity can be maintained and molding becomes easy.
The average chlorine content of the post-chlorinated vinyl chloride resin is preferably 58 to 70% by mass, particularly 60 to 70% by mass. If the average chlorine content is too low, the heat resistance is lowered and deformation is likely to occur. Conversely, if it is too high, the fluidity is greatly reduced and molding becomes difficult.

  The average degree of polymerization of the chlorine-containing resin is preferably 300 to 2,000, more preferably 500 to 1,500. If the average degree of polymerization is too small, the molded resin may not have sufficient strength, and if it is too large, it may be difficult to knead sufficiently during molding and workability may be reduced.

  The glass transition temperature (hereinafter also referred to as Tg) of the chlorine-containing resin is preferably in the range of 50 ° C. or higher and 120 ° C. or lower, particularly in the range of 70 ° C. or higher or 90 ° C. or lower in terms of moldability. Is even more preferable.

  Component A may include other thermoplastic resins, commercially available stabilizers, lubricants, impact modifiers, processing aids, heat improvers, matting agents, cross-linking agents, fillers, foaming agents, electrification as necessary. An anti-fogging agent, an anti-fogging agent, a plate-out preventing agent, a flame retardant, a fluorescent whitening agent, an antifungal agent, a metal deactivator, a pigment, a dye, an antioxidant, a light stabilizer and the like may be contained.

(Component B)
Component B in this film is a component mainly composed of a chlorine-free resin (hereinafter also referred to as “component B resin”) having a mass average molecular weight (Mw) in the range of 50,000 to 400,000.
Here, the component mainly composed of a chlorine-free resin means that the component B contains a component other than the chlorine-free resin, and the proportion of the chlorine-free resin in the component B is 50 mass. %, Preferably 70% by mass or more, more preferably 90% by mass or more, including 100% by mass.

If Mw of component B resin is 50,000 or more, bleeding and elution to the surface of this film can be reduced. Further, if Mw is 400,000 or less, there is no problem that the melt viscosity is too high and the molding processability is poor.
From this viewpoint, the Mw of the component B resin is more preferably in the range of 100,000 or more or 300,000 or less.
Here, the mass average molecular weight (Mw) was determined by gel permeation chromatography using chloroform as a solvent, a solution concentration of 0.2 wt / vol%, a solution injection amount of 200 μl, a solvent flow rate of 1.0 ml / min, and a solvent temperature of 40. It can be measured at ° C and calculated in terms of polystyrene.

Further, from the viewpoint of making the film excellent in transparency, the component B resin is preferably completely compatible with the component A resin.
Here, “completely compatible” means that the mixed resin of component B and component A has a single glass transition temperature (this point will be described in detail later), and components A and B are molecules. It is compatible at the level and does not take the sea-island structure.

As the component B resin, those having Mw in the above-mentioned range and preferably completely compatible with the component A resin can be appropriately selected from known thermoplastic resins. Among them, polyester resins, in particular polyester resins containing one or more dicarboxylic acids selected from the group consisting of succinic acid, adipic acid and terephthalic acid, and 1,4-butanediol as copolymerization components. Can be preferably exemplified.
Since all of these polyester resins are soft resins and have properties compatible with Component A resin, blending with Component A resin allows the elongation properties and low elution properties of this film. In addition, the transparency can be remarkably increased.

Furthermore, the polyester resin may be copolymerized with a diol other than 1,4 butanediol as long as the characteristics of the present invention are not impaired.
Examples of diols that can be used in this case include 1,3-propanediol, 1,4-cyclohexanedimethanol, 2,3-butanediol, 1,3-butanediol, 1,4-pentanediol, , 4-pentanediol, 1,6-hexanediol, neopentyl glycol, ethylene glycol, diethylene glycol and the like. These can be used alone or in combination of two or more.

  The polyester-based resin may be copolymerized with a dicarboxylic acid other than succinic acid, adipic acid, and terephthalic acid as long as the characteristics of the present invention are not impaired. Examples of the dicarboxylic acid that can be used include suberic acid, sebacic acid, itaconic acid, dodecanedioic acid, and cellulose acetate. These can be used alone or in combination of two or more.

Examples of the polyester-based resin that can be suitably used for the film include polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), and polybutylene succinate adipate (PBSA).
Among these, polybutylene succinate (PBS) and polybutylene succinate adipate (PBSA) using succinic acid which is a plant-derived component are particularly preferable.

Furthermore, the polyester resin may contain an aliphatic oxycarboxylic acid unit.
In this case, specific examples of the aliphatic oxycarboxylic acid that gives the aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy -3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, etc., or lower alkyl esters or intramolecular esters thereof.
When optical isomer resin exists in these, any of D resin, L resin, or racemic resin may be sufficient, and it may be solid resin, liquid resin, or aqueous solution as a form. Of these, lactic acid or glycolic acid is particularly preferred. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more.
The amount of the aliphatic oxycarboxylic acid is usually 0 mol% or more, preferably 0.01 mol% or more, based on the total amount of the single resin component constituting the polyester resin (100 mol%), The upper limit is usually 30 mol% or less, preferably 20 mol% or less.

  In addition, as the polyester-based resin, “trifunctional or higher aliphatic polyhydric alcohol”, “trifunctional or higher aliphatic polyhydric carboxylic acid or acid anhydride thereof”, or “trifunctional or higher aliphatic polyhydric oxyoxygen”. What copolymerized "carboxylic acid" is preferable at the point which can raise the melt viscosity of the polyester-type resin obtained.

Specific examples of the trifunctional aliphatic polyhydric alcohol include, for example, trimethylolpropane and glycerin. These may be used alone or in combination of two or more.
Specific examples of the tetrafunctional aliphatic polyhydric alcohol include, for example, pentaerythritol.
Specific examples of the trifunctional aliphatic polyvalent carboxylic acid or acid anhydride thereof include propanetricarboxylic acid or acid anhydride thereof.
Specific examples of the tetrafunctional polycarboxylic acid or its acid anhydride include, for example, cyclopentanetetracarboxylic acid or its acid anhydride. These may be used alone or in combination of two or more.

The trifunctional aliphatic oxycarboxylic acid includes (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Any type can be used. Specifically, malic acid or the like is preferably used.
The tetrafunctional aliphatic oxycarboxylic acid has (i) a type in which three carboxyl groups and one hydroxyl group are shared in the same molecule, and (ii) two carboxyl groups and two hydroxyl groups. Types that are shared in the same molecule, (iii) are divided into types that share three hydroxyl groups and one carboxyl group in the same molecule, and any type can be used. Specific examples include citric acid and tartaric acid. These may be used alone or in combination of two or more.

  The amount of such a tri- or higher functional compound is usually 0 mol% or more, preferably 0.01 mol% or more, based on the total amount of the single monomer resin constituting the polyester resin (100 mol%), and the upper limit. Is usually 5 mol% or less, preferably 2.5 mol% or less.

The preferred range of the molar ratio of the diol component to the dicarboxylic acid component for obtaining a polyester resin having a desired degree of polymerization varies depending on the purpose and the type of raw material. For example, the amount of the diol component relative to 1 mol of the acid component is 0.8 mol or more, preferably 0.9 mol or more, and the upper limit is usually 1.5 mol or less, preferably 1.3 mol or less, particularly preferably 1. 2 mol or less.
In addition, a urethane bond, an amide bond, a carbonate bond, an ether bond, or the like can be introduced into the polyester resin as long as the characteristics of the present invention are not affected.

The glass transition temperature (Tg) of Component B resin is preferably in the range of −80 ° C. to 30 ° C. If the Tg of Component B resin is −80 ° C. or higher, practical physical properties can be expressed, and if it is 30 ° C. or lower, the adhesive effect at room temperature is too strong, resulting in inferior molding processability. Absent.
From this point of view, the glass transition temperature (Tg) of the component B resin is more preferably −60 ° C. or higher or 0 ° C. or lower, and particularly preferably −50 ° C. or higher or −20 ° C. or lower. preferable.

  The melt flow rate (MFR) of Component B resin is usually 0.1 g / 10 min or more when measured at 190 ° C. and a load of 2.16 kg. Moreover, an upper limit is 100 g / 10min or less normally, Preferably it is 50 g / 10min or less, Most preferably, it is 30 g / 10min or less.

  A commercially available product can also be used as the component B resin. For example, “Ecoflex” series manufactured by BASF Corporation, “GSPla” series manufactured by Mitsubishi Chemical Corporation, “Bionore” series manufactured by Showa High Polymer Co., Ltd., “Cell Green” series manufactured by Daicel Chemical Industries, Ltd., etc. Are commercially available.

(Lubricant)
The kind of lubricant used for this film is not particularly limited. From the viewpoint of compatibility with Component B, an ester of a fatty acid and pentaerythritol or an ester of a fatty acid and dipentaerythritol can be preferably exemplified. These may be used alone or in combination of two or more.

  Examples of fatty acids in the lubricant include succinic acid, adipic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and other saturated linear fatty acids, sorbic acid, cinnamic acid, myristoleic acid, oleic acid, linoleic acid, and linolenic acid. Examples thereof include unsaturated fatty acids such as acids. Among these, it is preferable to use an unsaturated fatty acid such as adipic acid, an ester of oleic acid and pentaerythritol because the balance between the effect of imparting slipperiness and the antifogging property can be more effectively imparted to the film.

It is important that the content of the lubricant when the total content of the component A and the component B is 100 parts by mass is in the range of 0.1 parts by mass or more and 5 parts by mass or less, preferably 0. 2 parts by mass or more and 4.5 parts by mass or less, more preferably 0.3 parts by mass or more and 4 parts by mass or less. If the content of the lubricant is less than 0.1 parts by mass, the slip of the melt of the resin composition X in the mold is too low, so that the adhesion to the metal surface becomes too high, and the chlorine-containing resin itself is Thermal degradation causes film formation to be difficult. Moreover, when there is more content of a lubricant than 5 mass parts, phenomena, such as a fall of anti-fogging property of a film, generation | occurrence | production of a film nonuniformity, and the protrusion phenomenon at the time of long-term storage, will occur easily.
However, as the content of Component B increases, the range of the lubricant content that can make the sliding speed within the specified range becomes narrower, so the content of Component B is the total content of Component A and Component B. When the content is 30 parts by mass or more, the content ratio of the lubricant to the content of the component B (lubricant / component B) is preferably 0.001 to 0.060, particularly 0.005 or more or 0.045. Of these, 0.010 or more or 0.030 or less is particularly preferable.

(Anti-fogging agent)
The film preferably further contains an antifogging agent.
As the antifogging agent, for example, monoglycerin fatty acid ester, diglycerin fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, and polyoxyethylene alkyl ether can be particularly preferably used from the viewpoint of compatibility and color tone. These may be used alone or in combination of two or more.
Among them, at least polyethylene glycol fatty acid ester is included, that is, polyethylene glycol fatty acid ester is used alone, or polyethylene glycol fatty acid ester, monoglycerin fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, etc. are used in combination. Is preferable from the viewpoint of stable antifogging expression.

The monoglycerin fatty acid ester is preferably at least one compound selected from the group consisting of saturated fatty acids having 12 to 18 carbon atoms and glycerin esters of unsaturated fatty acids.
Specific examples of the compound include monoglycerol laurate, monoglycerol palmitate, monoglycerol stearate, and monoglycerol oleate. Among these, monoglycerol oleate is preferable.

The diglycerin fatty acid ester is preferably at least one compound selected from the group consisting of saturated fatty acids having 12 to 18 carbon atoms and unsaturated fatty acid diglycerin esters.
Specific examples of the compound include diglycerin laurate, diglycerin palmitate, diglyceryl stearate, and diglycerin oleate. Among these, diglycerin oleate is preferable.

  The sorbitan fatty acid ester is preferably a sorbitan ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms. Specific examples include sorbitan laurate, sorbitan myristate, sorbitan palmitate, sorbitan stearate, sorbitan oleate, sorbitan renolate and the like.

The polyethylene glycol fatty acid ester is preferably at least one compound selected from the group consisting of saturated fatty acids having 10 to 20 carbon atoms and polyethylene glycol esters of unsaturated fatty acids.
Specific examples of the compound include polyethylene glycol decanate, polyethylene glycol laurate, polyethylene glycol myristylate, polyethylene glycol palmitate, polyethylene glycol stearate, and polyethylene glycol oleate. Furthermore, the form of the ester may be either a monoester or a diester, but in order to obtain a higher effect, the monoester is preferable.

  The polyoxyethylene alkyl ether is preferably a saturated alcohol polyoxyethylene alkyl ether having 12 to 18 carbon atoms, more preferably a polyoxyethylene alkyl ether having 3 to 7 added moles of ethylene oxide. is there. Specific examples include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene palmityl ether, and polyoxyethylene stearyl ether.

When the total content of the component A and the component B is 100 parts by mass, the content of the antifogging agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and particularly preferably 3 parts by mass or more. More preferably. The upper limit of the content is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and particularly preferably 8 parts by mass or less.
If the content of the antifogging agent is 1 part by mass or more, it is preferable because good antifogging properties can be obtained, moldability to food packaging films, and sufficient packaging suitability can be obtained. Moreover, if content is 10 mass parts or less, since the bleed-out of the antifogging agent to the surface of this film does not arise easily and the transparency of this film can be maintained, it is preferable.

(Other ingredients)
Resin composition X can contain additives as needed in addition to the above-described components A, B, lubricants and antifogging agents.
Examples of the additive include a colorant, an inorganic filler, an organic filler, an ultraviolet absorber, a light stabilizer, an antioxidant, a hydrolysis inhibitor, an antistatic agent, and a plasticizer. The addition amount of these additives is not particularly limited, and can be appropriately determined within a range that does not hinder the desired physical properties of the film.

(Resin composition X)
The resin composition X is a resin composition containing the component A, the component B, the lubricant, and, if necessary, the antifogging agent, and has a single glass transition temperature. It is preferable.

  Here, the single glass transition temperature of the resin composition X means that the resin composition X has a dynamic viscoelastic temperature dispersion at a strain of 0.1%, a frequency of 10 Hz, and a heating rate of 3 ° C./min. There is one main dispersion peak of loss modulus (E ") measured by measurement (dynamic viscoelasticity measurement of JIS K7198A method), in other words, one maximum value of loss modulus (E"). It means to do. When the glass transition temperature of the resin composition X is single, the obtained food packaging film can achieve excellent transparency.

The single glass transition temperature of the resin composition X means that there is one main dispersion peak of loss tangent (tan δ) measured in the dynamic viscoelasticity measurement for the resin composition X, in other words, It can also be said that there is one maximum value of the loss tangent (tan δ).
In addition to the dynamic viscoelasticity measurement, it is possible to confirm that the glass transition temperature is single by differential scanning calorimetry. Specifically, when the glass transition temperature is measured using a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min according to JIS K7121, only one inflection point indicating the glass transition temperature appears. It can also be said to be a thing.

  In general, a single glass transition temperature of a polymer blend composition means that the resin to be mixed is in a compatible state on the nanometer order (molecular level). Can be acknowledged. Therefore, it is preferable that component A and component B are compatible on the nanometer order (molecular level). Moreover, it is preferable that the component A and the lubricant are compatible with each other on the nanometer order (molecular level). Furthermore, it is preferable that the component B and the lubricant are compatible on the nanometer order (molecular level).

  The glass transition temperature of the resin composition X is represented by the temperature indicating the peak value of the main dispersion of the loss elastic modulus (E ″) measured by the temperature dispersion measurement of the dynamic viscoelasticity. It is preferable that the transition temperature is in the range from the glass transition temperature of the chlorine-containing resin to the glass transition temperature of the component B resin.

  The glass transition temperature of the resin composition X is preferably −60 to 20 ° C., more preferably −55 ° C. or higher or 20 ° C. or lower, and further −40 ° C. or higher or 5 ° C. or lower. preferable. If the glass transition temperature of the resin composition X is within such a range, a more excellent food packaging film can be provided by container packaging.

In the resin composition X, it is important that the mass ratio of the content of Component A and Component B is in the range of 99: 1 to 55:45. The mass ratio is more preferably 90:10 to 60:40, and particularly preferably in the range of 80:20 to 60:40.
When the mass ratio of the content of component A and component B exceeds 99: 1 and component A increases, it is difficult to obtain a sufficient softening effect, which is not preferable. On the other hand, when the mass ratio exceeds 55:45 and the amount of component B increases, the melt tension decreases, the film-forming property of the film deteriorates, and the dispersibility deteriorates.

  The content of the plant-derived component in the resin composition X is preferably 25% by mass or more, particularly 30% by mass or more, and more preferably 40% by mass or more. As an upper limit, it is about 90 mass% from a viewpoint of the plant origin ratio which comprises component B resin.

In addition, it is important that the resin composition X has a sliding speed at a temperature of 190 ° C. and a wall shear stress of 1 × 10 ⁵ Pa within a range of 0.1 mm / sec to 10 mm / sec.

Here, the sliding speed is a Smooth nozzle with a flow tester CFT-500C manufactured by Shimadzu Corporation, the inner wall surface of which is chrome-plated, and an arithmetic average roughness Ra = 10 μm where the surface roughness of the inner wall surface is measured based on JIS B0601. For the Groove nozzle, the flow rate of the resin composition X at a temperature of 190 ° C. and a wall shear stress of 1 × 10 ⁵ MPa is measured and calculated by the following equation (1). Each nozzle has the same cross-sectional area.
V = (Q _smooth -Q _groove ) / S (1)
Here, in the above formula (1), V [mm / sec]: sliding speed, Q _smooth [mm ³ / sec]: flow rate at the Smooth nozzle, Q _groove [mm ³ / sec]: flow rate at the Groove nozzle, S [ mm ² ]: the cross-sectional area of each nozzle.

  Since the slip behavior of the chlorine-containing resin melt occurs between the chlorine-containing resin and the metal wall surface and does not occur inside the chlorine-containing resin, the apparent flow is both a slip flow and a viscous flow in a smooth nozzle with a smooth wall surface. It is said that it contains. For this reason, when a Groove nozzle with moderate irregularities is used, a chlorine-containing resin enters the irregularities, so that a chlorine-containing resin melt is formed on the wall surface, and the flow is only viscous flow. Therefore, the sliding flow and viscous flow of the chlorine-containing resin can be separated by using the two types of nozzles.

  The inventors have found that a film having a good appearance can be obtained by controlling the sliding speed of the resin composition X within a predetermined range. That is, when the sliding speed of the resin composition X is less than 0.1 mm / sec, the slipping property of the melt in the mold is too low, and thus the adhesiveness with the metal surface becomes too high, and the chlorine-containing resin itself is Thermal degradation causes film formation to be difficult. On the other hand, if the sliding speed of the resin composition X is larger than 10 mm / sec, the slipping property of the melt in the mold is too high, so that the sliding flow is dominant in the mold and the film appearance due to flow unevenness is deteriorated. .

  At this time, the sliding speed of the resin composition X is set to the above range by further adjusting the composition ratio of the component A, the component B and the lubricant to the above-described range as necessary. be able to. In this case, for example, if the composition ratios of component A and component B are different, the range of the content of the lubricant for making the sliding speed of the resin composition X be in the above range is also different. More specifically, as the content ratio of component B increases, the upper limit value of the content range of the lubricant in which the sliding speed of the resin composition X falls within the above range decreases. Therefore, as described above, when the content of component B is 30 parts by mass or more of the total content of component A and component B, the content ratio of the lubricant to the content of component B (lubricant / component B) ) Is preferably 0.001 to 0.060, more preferably 0.005 or more and 0.045 or less, and particularly preferably 0.010 or more or 0.030 or less.

(This film)
This film can be obtained by molding the resin composition X.

  The method for forming the film from the resin composition X is not particularly limited, and a known appropriate method such as an extrusion casting method using a T-die or an inflation method may be employed.

  The thickness of this film becomes like this. Preferably they are 7 micrometers-12 micrometers, More preferably, they are 8 micrometers-11 micrometers. By being in this range, this film can be suitably used for food packaging.

The film has excellent elongation characteristics at room temperature, and the tensile elongation in the MD direction measured according to JIS K7161 is preferably 100% or more and 150% or more under a temperature condition of 23 ° C. More preferably, it is particularly preferably 200% or more.
In order to make the tensile elongation rate in such a range, for example, the ratio of the component A and the component B may be adjusted within the aforementioned range. However, the adjustment means is not limited to this.

This film is excellent in low elution, and the n-heptane extraction amount measured by the evaporation residue test method (both sides method) defined in Ministry of Health and Welfare Notification No. 20 can be 10 ppm or less, more preferably 9 ppm or less. It can be.
In order to make the n-heptane extraction amount within such a range, for example, the amounts of component B, lubricant and antifogging agent may be adjusted within the above-mentioned ranges. However, the adjustment means is not limited to this.

Since this film has a small film unwinding force, it can be easily unwound at the time of use. The paper tube around which the film having a width of 50 mm is wound is smoothly rotated and unwound at an unwinding speed of 3 cm / sec. The load at the time is preferably 1.5 N or less, particularly preferably 1.4 N or less, and particularly preferably 1.3 N or less.
In order to make the film unwinding force within such a range, for example, the ratio of component A and component B may be adjusted within the above-mentioned range. However, the adjustment means is not limited to this.

This film is excellent in anti-fogging properties, for example, water is put into a PP container having a length of 11.5 cm, a width of 11.5 cm, and a depth of 6 cm, and then wrapped in a film, and the temperature is 0 to 5 ° C. Even when stored in a refrigerator with a relative humidity of 25 to 35% RH for 1 hour, the water content does not condense on the film surface and the contents can be clearly confirmed. Even if moisture condenses on the film surface, the water film does not become a lens shape and the contents can be confirmed uniformly and clearly.
In order to have such an antifogging property, for example, the amount of the antifogging agent may be adjusted within the aforementioned range. However, the adjustment means is not limited to this.

<Explanation of terms>
“Sheet” generally refers to a product that is thin by definition in JIS and generally has a thickness that is small and flat for the length and width. In general, “film” is compared to the length and width. A thin flat product with an extremely small thickness and an arbitrarily limited maximum thickness, usually supplied in the form of a roll (JIS K6900). For example, in terms of thickness, in the narrow sense, a film having a thickness of 100 μm or more is sometimes referred to as a sheet, and a film having a thickness of less than 100 μm is sometimes referred to as a film. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

In the present invention, when expressed as “P to Q” (P and Q are arbitrary numbers), “P is preferably greater than P” and “preferably Q”, with the meaning of “P to Q” unless otherwise specified. It means “smaller”.
Further, in the present invention, when expressed as “P or more” (Q is an arbitrary number), it means “preferably larger than P” unless otherwise specified, and “Q or less” (Q is an arbitrary number). ) Includes “preferably smaller than Q” unless otherwise specified.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited by the following Example.

<Raw material>
First, the raw materials used in Examples and Comparative Examples will be described.

(Component A)
As the chlorine-containing resin, a vinyl chloride resin having an average degree of polymerization of 1030, a mass average molecular weight of 60,000, and Tg of 82 ° C. was used.

(Component B)
(B-1): polybutylene succinate adipate which is a condensation polymer of 1,4-butanediol and succinic acid, adipic acid and lactic acid (mass average molecular weight: 170,000, acid component: succinic acid 74 mol%, Adipic acid 20 mol%, lactic acid 6 mol%, Tg: −40 ° C., MFR (190 ° C., 2.16 kg load): 4.5 g / 10 min, plant-derived component: 85.7% were used.
(B-2): polybutylene adipate terephthalate which is a condensation polymer of 1,4-butanediol, adipic acid and terephthalic acid (mass average molecular weight: 160,000, acid component: 52 mol% adipic acid, 48 mol terephthalic acid %, Tg: −28 ° C., MFR (190 ° C., 2.16 kg load): 2.5 g / 10 min, plant-derived component: 0%.
(B-3): polybutylene adipate which is a condensation polymer of 1,3-butanediol and adipic acid (mass average molecular weight: 0.060,000, acid component: 100 mol% adipic acid, plant-derived component: 0%) Trade name “W-360EL” manufactured by Dainippon Ink, Inc. was used.
(B-4): Diisononyl adipate (mass average molecular weight: 0.040,000), trade name “DINA” manufactured by J-Plus was used.

(Lubricant)
As a lubricant, pentaerythritol adipate oleate (trade name “Loxiol-G71S” manufactured by Cognis Co., Ltd.), which is a pentaerythritol fatty acid ester, was used.

(Anti-fogging agent)
As anti-fogging agents, glycerin laurate (trade name “Riquemar L-71” manufactured by Riken Vitamin Co., Ltd.) which is a glycerin fatty acid ester, and sorbitan oleate (trade name “Emanon O-10V” manufactured by Kao Corporation) which is a sorbitan fatty acid ester. )).

(Stabilizer)
As a calcium zinc stabilizer (CaZn stabilizer), a product name “Adeka Stub SC-320” manufactured by Adeka Corporation was used.
As the epoxidized soybean oil, a trade name “S300” (ratio of plant-derived component 95 mass%) manufactured by Daicel Chemical Industries, Ltd. was used.

<Examples and comparative examples>
Component A, Component B, Lubricant, Anti-fogging agent and stabilizer (1 part by weight of calcium zinc-based stabilizer, 18 parts by weight of epoxidized soybean oil) in the proportions shown in Table 1 (content of each raw material is shown in parts by weight) ) Were weighed and mixed with a Henschel mixer to obtain a resin composition X. The resin composition X was set using a single screw extruder so that the resin temperature was 200 ° C., and melt extrusion film formation was performed by a T-die method to obtain a film (sample) having a thickness of 10 μm.

<Evaluation method>
The raw materials used in the examples and comparative examples, and the resin compositions X and films (samples) obtained in the examples and comparative examples were measured and evaluated by the following methods, and the results are shown in Table 1. In addition, the flow direction at the time of film forming is called MD, and the orthogonal direction to MD is called TD.

(Mass average molecular weight)
By gel permeation chromatography, measurement was carried out using chloroform as the solvent at a solution concentration of 0.2 wt / vol%, a solution injection amount of 200 μl, a solvent flow rate of 1.0 ml / min, and a solvent temperature of 40 ° C. The mass average molecular weight (Mw) of the resin was calculated and evaluated according to the following criteria.
○: Mw of component B resin is 50,000 or more and 400,000 or less ×: Mw of component B resin is less than 50,000 or more than 400,000

(Sliding speed)
Using a flow tester CFT-500C manufactured by Shimadzu Corporation, a smooth nozzle (cross-sectional area: 800 mm ² ) whose inner wall surface is chrome-plated, and an arithmetic average roughness Ra = 10 μm, the surface roughness of the inner wall surface measured based on JIS B0601 For the Groove nozzle (cross-sectional area: 800 mm ² ), the flow rate of the resin composition X at a temperature of 190 ° C. and a wall shear stress of 1 × 10 ⁵ MPa was measured, and the sliding speed was calculated according to the above formula (1). It was evaluated with.
○: 0.1 mm / sec or more and 10 mm / sec or less ×: less than 0.1 mm / sec or greater than 10 mm / sec

(appearance)
The films (samples) prepared in Examples and Comparative Examples were visually observed and evaluated according to the following criteria.
○: There is no unevenness and the contents can be clearly confirmed.
(Triangle | delta): Although the nonuniformity has generate | occur | produced in part, the content can be confirmed clearly.
X: Unevenness occurs in the entire width and the contents cannot be clearly confirmed.

(Film unwinding property)
A pipe made of vinyl chloride resin is wound around a cylindrical paper tube (outer diameter 85 mm, width 330 mm) by winding a film (sample) of 50 mm width and 10 μm thickness by 10 m so that the film roll rotates smoothly. (Outer diameter 25 mm) was inserted. Then, while holding the film tip with a clip so that the width is constant, the load applied when the film is unwound at the unwinding speed of 3 cm / sec is measured using a force gauge. Evaluation was made according to the following criteria.
○: 1.5N or less ×: Greater than 1.5N

(Anti-fogging property)
Put water (23 ° C.) into a PP container having a length of 11.5 cm, a width of 11.5 cm, and a depth of 6 cm, and then seal the opening of the container with a film (sample). The film was packaged and stored in a refrigerator at a temperature of 0 to 5 ° C. and a relative humidity of 25 to 35% RH for 1 hour, and the degree of haze after storage was evaluated according to the following criteria.
○: The contents can be clearly confirmed without condensation.
Δ: Condensation but water film is uniform and contents can be clearly confirmed.
×: Condensed and the water film is non-uniform and becomes a lens shape, and the contents cannot be clearly confirmed.

(Elution)
The n-heptane extract amount (ppm) of the film (sample) was measured by the evaporation residue test method (double-sided method: so-called dipping method) defined in Ministry of Health and Welfare Notification No. 20, and evaluated according to the following criteria.
○: 10 ppm or less ×: More than 10 ppm

In Examples 1 to 4, when a part of the resin composition as an intermediate substance was taken out and the glass transition temperature was measured, a single glass transition temperature was measured. Therefore, the resin compositions of Examples 1 to 4 were It was confirmed that they were completely compatible.
Further, as is clear from Table 1, the films (samples) obtained in Examples 1 to 4 were excellent in appearance, film unwinding property, antifogging property, and low elution property. On the other hand, the film (sample) obtained in Comparative Example 1-7 had a problem in any of the evaluation of appearance, film unwinding property, antifogging property, and low elution property. When especially Example 1-4 and Comparative Example 3-7 are compared, the external appearance of a film, film unwinding property, anti-fogging property, and by making the sliding speed of a resin composition into the range of 0.1-10 mm / sec. It was found that low elution can be improved in a well-balanced manner.

In addition, when Example 1 and Example 2 are compared, although Mw of the component B does not differ greatly, the sliding speed differs greatly. This is because B-1 is an aliphatic carboxylic acid called succinic acid and adipic acid, and B-2 is copolymerized with terephthalic acid, which is an aromatic carboxylic acid, in addition to adipic acid. It is inferred that it gives a difference in the activity of.
Moreover, about the comparative example 7, when film unwinding property was tested, after winding a film (sample), even if the film was pulled in the horizontal direction, it was not able to be peeled off and unwound.

Claims (5)

A film for food packaging formed by molding a resin composition X containing the following component A, the following component B, and a lubricant, wherein the content of the following component A and the following component B in the resin composition X The mass ratio is in the range of 99: 1 to 55:45, and the content of the lubricant is 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the total content of the following component A and the following component B. A film for food packaging, wherein the resin composition X has a sliding speed at a temperature of 190 ° C. and a wall shear stress of 1 × 10 ⁵ Pa within a range of 0.1 mm / sec to 10 mm / sec.
Component A: Component mainly composed of chlorine-containing resin Component B: Component mainly composed of chlorine-free resin having a mass average molecular weight (Mw) of 50,000 to 400,000   The film for food packaging according to claim 1, wherein the lubricant is an ester of fatty acid and pentaerythritol, an ester of fatty acid and dipentaerythritol, or a mixed resin of these two types of esters. .   The chlorine-free resin is a polyester resin containing one or more dicarboxylic acids selected from the group consisting of succinic acid, adipic acid and terephthalic acid, and 1,4-butanediol as copolymerization components. The film for food packaging according to claim 1 or 2, wherein the film is for food packaging.   The food packaging film according to claim 1, wherein the resin composition X further contains an antifogging agent.   5. The load when a film having a width of 50 mm and a thickness of 10 μm is unwound at a speed of 3 cm / sec in the horizontal direction with respect to the ground is 1.5 N or less. 5. Food packaging film.