JP7105713B2 - Resin film and its manufacturing method - Google Patents

Description

The present invention relates to a resin film and its manufacturing method.

Vinylidene chloride-based resin films are widely used as wrap films and the like because they have properties such as impermeability to oxygen and moisture, high adhesion, high heat resistance, and high transparency.

A wrap film is usually stored in a storage box as a wound body wound into a roll. As the storage box, a storage box is known which has a main body portion for storing the wound body and a cover portion which is rotatably connected to the main body portion. A user of the wrap film holds the end portion of the wrap film housed in the main body and pulls the end portion while rotating the wound body to squeeze the amount of wrap film to be used between the main body and the lid. By pulling it out from the gap and cutting it with a cutting blade provided on the lid, the required length of the wrap film can be taken out from the storage box. At this time, the end portion of the wound body after cutting is adhered to and locked to the body portion in order to facilitate the next delivery.

The vinylidene chloride-based resin film is produced by melt-extruding a vinylidene chloride-based resin composition obtained by a method such as suspension polymerization, and then stretching it into a film.

In Patent Document 1, by using a suspension dispersant during the suspension polymerization, the suspension stability is improved, and the particle size of the resulting vinylidene chloride resin is controlled to improve extrusion stability and uniform film thickness of the film. It is stated that it can enhance the Patent Document 1 describes that a good film was produced by using 500 ppm of a suspending agent with respect to 100 parts by mass of a monomer for synthesizing a vinylidene chloride resin.

Patent Literature 2 describes that by adding liquid paraffin to a polyvinylidene chloride-based film, the film can exhibit appropriate release performance.

WO2003/006548 JP-A-10-087876

By the way, in the wrap film stored as a roll in the storage box described above, the cut ends of the wrap film are wound back into the main body by the reverse rotation of the roll. (Hereinafter, simply referred to as “winding portion”.) The end may stick to the surface of the wrap film (hereinafter, the state in which the end of the wrap film sticks to the surface of the winding portion due to rewinding is also simply referred to as "rewinding state"). Here, since the wrap film is required to have high adhesion, the adhesion between the wrap films is also very high. Therefore, when trying to restore the state in which the ends are separated from the winding portion by peeling off the stuck ends from the winding portion, the end portions of the wrap film are pinched and a large force is applied to the outside. It needs to be pulled, and the force on the edges at this time tends to tear the wrap film in the machine direction (MD). When trying to restore the wrap film so as not to tear it in the vertical direction, the restoration takes time.

On the other hand, if liquid paraffin is added to improve the releasability of the resin film used as the wrap film as described in Patent Document 2, it is thought that the wrap film can be easily recovered from the unwound state. However, according to the findings of the present inventors, if an attempt is made to reduce the amount of liquid paraffin due to the tightening of regulations in recent years, the peelability of the resin film cannot be sufficiently improved, and during restoration, the resin in the vertical direction cannot be removed. Film tearing cannot be sufficiently suppressed.

In view of the above problems, the present invention provides a resin film that does not tear in the longitudinal direction and allows the end portion to be easily peeled off from the wound portion in the unwound state, and a method for producing such a resin film. Its purpose is to

A resin film relating to one aspect of the present invention for solving the above problems is a resin film made of a vinylidene chloride resin composition, wherein the surface adhesion value ( N) ratio (value of plane adhesion/value of tear strength to MD) is 0.35 or more and less than 0.41.

Further, a method for producing a resin film according to another aspect of the present invention for solving the above problems comprises the step of stretching a melted and extruded vinylidene chloride resin composition, and the stretched vinylidene chloride resin and relaxing the composition. The vinylidene chloride resin composition contains a monomer for synthesizing a vinylidene chloride resin by polymerization in the presence of a water-soluble cellulose derivative having a content of 300 ppm or more and 600 ppm or less with respect to the total mass of the monomer. It is a resin composition obtained by suspension polymerization in an aqueous medium. In the production method, in the stretching step, the vinylidene chloride resin composition is stretched in the MD at a draw ratio of 3.5 to 5.0 times and in the TD at a draw ratio of 4.0 to 5.5. In the step of stretching the stretched vinylidene chloride resin composition so as to be 100% or less and relaxing, the stretched vinylidene chloride resin composition is relaxed so that the relaxation rate to MD is 9.5% or more and 12.5% or less.

ADVANTAGE OF THE INVENTION According to this invention, the resin film and the manufacturing method of such a resin film which can be easily peeled off from the winding part of the unwound state without causing tearing of the resin film in the longitudinal direction are provided.

[Resin film]
(physical properties, etc.)
One embodiment of the present invention relates to a resin film made of a vinylidene chloride resin composition. In the resin film, the ratio of the surface adhesion value (unit: N) to the MD tear strength value (unit: mN) (surface adhesion value (N) / tear strength value to MD (mN ).Hereinafter, this ratio is also simply referred to as a “recovery factor.”) is 0.35 or more and less than 0.41.

In addition, MD means the winding direction of the resin film wound in roll shape. Moreover, TD means a direction orthogonal to MD in the plane of the resin film.

In order for the resin film made of the vinylidene chloride-based resin composition to be easily restored from the unwound wound portion without causing tearing of the resin film in the longitudinal direction, the surface adhesion value is lower. It is desirable that the tear strength to the MD be higher. However, in order to sufficiently secure the adhesiveness of the resin film to the container or the like, it is not desirable to reduce the surface adhesiveness too much.

From these points of view, in this embodiment, the recovery coefficient is set to 0.35 or more and less than 0.41. When the recovery coefficient is 0.35 or more, the surface adhesion of the resin film is not excessively lowered, and the adhesion to containers and the like is sufficiently ensured. On the other hand, when the recovery coefficient is less than 0.41, the tear strength of the resin film to the MD increases moderately, while the surface adhesion strength decreases moderately. It is easy to restore the unwound resin film. From the above viewpoint, the recovery coefficient is preferably 0.36 or more and 0.40 or less, and more preferably 0.37 or more and 0.40 or less.

The value of the tear strength to the MD can be a value measured using a known tear tester. Specifically, a test piece obtained by cutting the resin film to a size of 63.5 mm in the length direction (MD) x 50 mm in the width direction (TD) is set in the center of the clamp of the tear tester, and the length A cut is made with a knife in the center of the width direction (TD) of the test piece so that the cut length in the direction (MD) is 12.7 mm, and the pendulum is opened to cut the test piece. The maximum load for tearing the test piece at this time can be taken as the value of the tear strength (unit: mN) of the test piece to the MD.

The surface adhesion force can be a value measured using a known tensile tester. Specifically, the resin film was fixed to two aluminum columnar jigs having a base area of 25 cm ² and a mass of 300 g while tensioning the bottom surfaces of the two jigs so as not to cause wrinkles. The resin films fixed to the tool are brought into contact with each other in the vertical direction and crimped. After that, the two jigs are pulled in opposite vertical directions using a tensile tester. The maximum load (unit: N) for separating the jig at this time can be taken as the value of the surface contact force of the test piece.

From the viewpoint of facilitating adjustment of the recovery coefficient to the range described above, the resin film preferably has a value of tear strength to the MD of 32.0 mN or more and 34.5 mN or less, and 32.5 mN or more. It is more preferably 34.5 mN or less, and further preferably 33.0 mN or more and 34.5 mN or less. When the value of the tear strength to the MD is 32.0 mN or more, the resin film is less likely to be longitudinally torn during restoration or other uses, and thus the ease of use of the resin film can be further enhanced.

Further, from the viewpoint of facilitating adjustment of the restoration coefficient within the range described above, it is preferable that the resin film has a surface adhesion value of 12.0 N or more and 13.0 N or less, and more preferably 12.0 N or more and 12.0 N or more. It is more preferably 5N or less. When the value of the surface adhesion strength is 12.0 N or more, the resin film easily adheres to a container or the like during use, so that the ease of use of the resin film can be further enhanced.

As will be described later, in the present embodiment, a vinylidene chloride-based resin composition containing a vinylidene chloride-based resin polymerized in the presence of a predetermined amount of a water-soluble cellulose derivative is stretched and relaxed at a predetermined ratio. A resin film that satisfies the value of the recovery factor can be produced. From the viewpoint of suppressing a decrease in the transparency of the resin film due to the water-soluble cellulose derivative used at this time, the haze value of the resin film is preferably 1.2% or less, and 0.8% or less. is more preferably 0.6% or less. Although the lower limit of the haze value is not particularly defined, it can be 0.05% or more.

The haze value can be a value obtained by measuring according to JIS K 7136 (2000).

In addition, from the viewpoint of further enhancing the transparency of the resin film, the resin film has an arithmetic surface roughness (Ra) defined in JIS B 0601 (2013) of greater than 5.0 nm and less than 20.0 nm. is preferably greater than 5.0 nm and less than or equal to 7.7 nm, and more preferably greater than 6.0 nm and less than 7.5 nm.

The arithmetic surface roughness (Ra) can be a value obtained using a known surface roughness measuring instrument.

Further, as will be described later, in the present embodiment, by stretching the vinylidene chloride-based resin composition at a higher draw ratio than in the past, it is possible to produce a resin film that satisfies the value of the recovery coefficient. Therefore, in the resin film according to the present embodiment, the vinylidene chloride resin molecules are oriented in the MD in a more tense state, making it easier to pierce with a cutting blade or the like, and cutting (especially cutting into the TD) is possible. easier. Specifically, the resin film preferably has a puncture strength value of less than 4.0N, more preferably less than 3.8N, and even more preferably less than 3.5N. Although the lower limit of the piercing strength is not particularly defined, it can be set to 1.5 N or more from the viewpoint of easily maintaining the shape of the resin film.

The puncture strength can be a value obtained by measuring according to JIS Z 1707 (2019).

Although the thickness of the resin film is not particularly limited, it can be 1 μm or more and 50 μm or less, preferably 4 μm or more and 45 μm or less, and more preferably 7 μm or more and 40 μm or less. When the thickness is 1 μm or more, the resin film can be made difficult to tear. When the thickness is 50 μm or less, the cuttability of the resin film is improved, and the feel of the film is improved.

The resin film may be a transparent resin film. In addition, the resin film has adhesiveness to foods, tableware, and the like. Therefore, the resin film can be suitably used as a wrap film.

Moreover, it is preferable that the resin film is stored as a wound body wound into a roll. The wound body has a body portion for storing the wound body and a lid portion rotatably connected to the body portion, and is housed in a storage box having a cutting blade in the lid portion. is preferred. The wound body housed in the storage box draws out the amount of resin film to be used from the gap between the main body part and the lid part by pulling the ends of the resin film while rotating the wound body, and puts it on the lid part. By cutting with the installed cutting blade, only the required length can be taken out of the storage box.

(composition, etc.)
The resin film is a single-layer film formed by forming a vinylidene chloride resin composition into a film.

The vinylidene chloride-based resin composition is a resin composition containing a vinylidene chloride-based resin as a main component.

The vinylidene chloride-based resin may be a homopolymer of vinylidene chloride or a copolymer containing structural units derived from vinylidene chloride.

The above copolymer is a copolymer of vinylidene chloride and a monomer copolymerizable with vinylidene chloride. Examples of monomers copolymerizable with vinylidene chloride include vinyl chloride, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate and stearyl acrylate. Methacryl having an alkyl group of 1 to 18 carbon atoms, including alkyl acrylates having 1 to 18 carbon atoms, methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and stearyl tacrylate. Acid alkyl esters, vinyl cyanide compounds including acrylonitrile and methacrylonitrile, aromatic vinyl compounds including styrene, vinyl esters of aliphatic carboxylic acids having 1 to 18 carbon atoms including vinyl acetate, 1 to 18 alkyl vinyl ethers, vinyl polymerizable unsaturated carboxylic acids including acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, vinyl polymerizable unsaturated carboxylic acids such as maleic acid, fumaric acid and itaconic acid Alkyl esters (which may be partial esters) in which the number of carbon atoms in the alkyl group of is 1 or more and 18 or less, and diene-based monomers. Among these, vinyl chloride, methyl acrylate and butyl acrylate are preferred, and vinyl chloride is more preferred.

In the copolymer, the ratio of structural units derived from vinylidene chloride to the total mass is preferably 60% by mass or more, more preferably 70% by weight or more, and further preferably 80% by weight or more. preferable. Although the upper limit of the proportion of structural units derived from vinylidene chloride is not particularly defined, it is preferably 98% by weight or less, more preferably 95% by weight or less, from the viewpoint of enhancing extrusion processability.

The vinylidene chloride resin preferably has a reduced viscosity of 0.035 or more and 0.070 or less, more preferably 0.040 or more and 0.065 or less. When the reduced viscosity is 0.035 or more, the extrusion workability of the vinylidene chloride resin composition can be further enhanced. When the reduced viscosity is 0.70 or less, coloring of the resin film is suppressed, and the vinylidene chloride resin composition can be melted more easily during molding.

From the viewpoint of further improving extrusion processability, the vinylidene chloride resin composition includes an ethylene/vinyl acetate copolymer, a copolymer of ethylene and acrylic acid, methacrylic acid or their alkyl esters, and an MBS resin ( It may further contain other resins such as methyl methacrylate-butadiene-styrene copolymer). The content of the other resin is preferably 0.1 parts by mass or more and 20 parts by mass or less, and 1.0 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the vinylidene chloride resin. is more preferable.

The vinylidene chloride resin composition may contain a water-soluble cellulose derivative when synthesizing the vinylidene chloride resin by suspension polymerization. The water-soluble cellulose derivative acts as a suspending agent during suspension polymerization, and also remains on the surface of the resin film to moderately roughen the surface of the resin film.

Examples of the above water-soluble cellulose derivatives include methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropoxymethylcellulose, carboxymethylcellulose and the like. Among these, methylcellulose, hydroxypropylcellulose, and hydroxypropoxymethylcellulose are more preferred, and methylcellulose is even more preferred.

The water-soluble cellulose derivative is preferably contained in an amount such that 15 μg or more per 1 m ² is extracted when the resin film is immersed in 100 ml of ethanol, heated to 70° C. and extracted for 5 hours. If the extraction amount of the water-soluble cellulose derivative under the above conditions is within the above range, the water-soluble cellulose derivative probably remains appropriately on the surface of the resin film and moderately roughens the surface of the resin film. It is possible to moderately reduce the surface adhesion force while substantially maintaining the tear strength to the MD. Therefore, it is easy to adjust the recovery coefficient to the range described above. Although the upper limit of the content of the water-soluble cellulose derivative extracted from the resin film is not particularly limited, it can be 100 μg or less, preferably 50 μg or less, more preferably 30 μg or less per 1 m ² of the resin film.

The vinylidene chloride resin composition may contain additives such as plasticizers, stabilizers and slip agents as long as they do not significantly affect the recovery coefficient.

Examples of such plasticizers include acetyl tributyl citrate, dioctyl phthalate, dibutyl sebacate, dioctyl sebacate, diacetylated monoglycerides, acetylated diglycerides and acetylated triglycerides. Examples of such stabilizers include epoxidized soybean oil (ESBO) and epoxidized linseed oil (ELO). The total content of the plasticizer and stabilizer is preferably 0.5 parts by mass or more and 10 parts by mass or less, and 1.0 parts by mass or more and 7.5 parts by mass or more, relative to 100 parts by mass of the vinylidene chloride resin. It is more preferably 0 parts by weight or less.

Examples of the above slip agents include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides and thioether compounds. The content of the slip agent is preferably 0.05 parts by mass or more and 10 parts by mass or less, and 0.1 parts by mass or more and 6.0 parts by mass or less with respect to 100 parts by mass of the vinylidene chloride resin. It is more preferable to have

Moreover, the vinylidene chloride-based resin composition may contain a tackifier.

Examples of the tackifier include sorbitan fatty acid esters such as sorbitan monooleate and sorbitan trioleate, propylene glycol fatty acid esters, glycerin fatty acid esters such as glycerin monooleate and glycerin trioleate, and liquid paraffin. .

However, the vinylidene chloride-based resin composition preferably does not substantially contain a tackifier. "Substantially free" means that the content of the tackifier is 100 ppm or less (preferably 50 ppm or less, more preferably 20 ppm or less) with respect to 100 parts by mass of the vinylidene chloride resin.

[Method for producing resin film]
The resin film described above can be produced by a method comprising a step of stretching the melted and extruded vinylidene chloride resin composition, and a step of relaxing the stretched vinylidene chloride resin composition. can.

(Preparation of vinylidene chloride resin composition)
The vinylidene chloride resin composition can be prepared by mixing the synthesized vinylidene chloride resin and various additives.

The vinylidene chloride-based resin can be synthesized by suspension polymerization of vinylidene chloride and a monomer copolymerizable with vinylidene chloride.

Specifically, vinylidene chloride (vinylidene chloride and a monomer copolymerizable with vinylidene chloride when synthesizing a copolymer) is added to the water-soluble cellulose in a reactor (polymerization machine) made of stainless steel or the like. Derivatives are present, suspended by stirring in an aqueous medium and dispersed in oil droplets. Thereafter, a polymerization initiator is added to the suspension, and the temperature is raised as necessary to polymerize vinylidene chloride (and the monomer copolymerizable with vinylidene chloride). The temperature at this time is usually 25 to 90° C., preferably 30 to 85° C., and the polymerization time is usually 1 to 100 hours, preferably 2 to 60 hours, more preferably 3 to 50 hours.

At this time, the amount of the water-soluble cellulose derivative added is 300 ppm or more and 600 ppm or less, preferably 300 ppm or more and 500 ppm or less with respect to 100 parts by mass of vinylidene chloride (and the monomer copolymerizable with vinylidene chloride). . By setting the amount of the water-soluble cellulose derivative within the above range, the water-soluble cellulose derivative remaining on the surface of the resin film probably moderately roughens the surface of the resin film, thereby improving the MD of the produced resin film. It is possible to moderately reduce the surface adhesion force while substantially maintaining the tear strength of . Therefore, it is easy to adjust the recovery coefficient of the manufactured resin film to the range described above.

The obtained vinylidene chloride resin and, if necessary, additives such as a plasticizer, a stabilizer and a slip agent contained in the resin film are mixed to prepare the vinylidene chloride resin composition. can. The above additives may be mixed at any time, and may be added to the suspension during polymerization, or the vinylidene chloride resin and the above additives may be mixed after polymerization. Mixing is performed by Henschel mixer, cylindrical mixer, screw mixer, screw extruder, turbulizer, Nauta mixer, V mixer, ribbon mixer, twin-arm kneader, fluid mixer, It can be carried out using a known mixing device such as an airflow mixer, a rotating disk mixer, a roll mixer, a tumbling mixer, and a Loedige mixer. Thereby, a powdery or pellet-like vinylidene chloride-based resin composition can be obtained.

(Molding of resin film)
The vinylidene chloride resin composition prepared above is melted and extruded by a known method, and then stretched and relaxed.

First, the vinylidene chloride resin composition is charged into an extruder, melted in a cylinder, and extruded through a die. The die may be a T-die that extrudes the vinylidene chloride resin composition into a flat plate, or a circular die that extrudes the vinylidene chloride resin composition into a tubular shape.

The extruded vinylidene chloride resin composition passes through a plurality of guide rollers and a plurality of pinch rollers and is wound up by a winding roller. At this time, by varying the rotation speed of the continuous pinch rollers among the plurality of pinch rollers, or by adjusting the amount of air when inflating the tubularly extruded vinylidene chloride resin composition, The extruded vinylidene chloride resin composition can be stretched in the MD (machine direction) at a predetermined ratio. Further, by using a tenter or adjusting the amount of air when inflating the tubularly extruded vinylidene chloride resin composition, the extruded vinylidene chloride resin composition can be TD at a predetermined ratio. It can be stretched (in the direction perpendicular to the flow). The vinylidene chloride-based resin composition stretched in the MD and TD is then relaxed in the MD due to the difference in rotational speed between successive pinch rollers.

In the present embodiment, it is possible to adjust the surface adhesion (recovery coefficient) with respect to the value of the tear strength of the resin film to be molded to the MD by the draw ratios in the MD and TD at this time and the relaxation rate in the MD. can.

Specifically, at this time, the draw ratio to MD is 3.5 times or more and 5.0 times or less, the draw ratio to TD is 4.0 times or more and 5.5 times or less, and the relaxation rate to MD is 9.5% or more and 12.5%.

The draw ratio to the MD is more preferably 3.5 times or more and 4.5 times or less, and further preferably 3.8 times or more and 4.5 times or less. The draw ratio to the TD is more preferably 4.5 times or more and 5.5 times or less, and further preferably 4.5 times or more and 5.0 times or less. The relaxation rate to MD is more preferably 10.5% or more and 12.0% or less, and further preferably 11.0% or more and 12.0% or less.

In this way, by increasing the draw ratio and increasing the subsequent relaxation rate, the molecules of the vinylidene chloride resin are easily oriented in the MD in a more tensed state, and the tear strength of the resin film to the MD is moderately increased. By increasing and relaxing, the surface of the resin film can be moderately roughened to moderately reduce surface adhesion. Furthermore, in the present embodiment, the vinylidene chloride-based resin composition containing a water-soluble cellulose derivative also moderately roughens the surface of the resin film, thereby moderately lowering the surface adhesion. By these actions, a resin film having a recovery coefficient of 0.35 or more and less than 0.41 is obtained, which does not tear in the longitudinal direction and can be easily peeled off from the wound part in the unwound state. It is possible and conceivable.

The stretched and relaxed vinylidene chloride resin composition is then taken up by a take-up roller.

The vinylidene chloride-based resin composition extruded into a tubular shape by a tubular die may then be cut in the direction of the extrusion axis to form a single-thickness flat film, or may be folded to form a double-thickness flat film. .

Hereinafter, the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited to the description of the examples.

1. Preparation of resin film 1-1. Preparation of resin film-1 Vinylidene chloride (VD) and vinyl chloride (VC) were mixed at VD:VC = 82:18 (mass ratio), water in which methylcellulose was dissolved, and acetyl tributyl site as an additive. (ATBC), diacetylated monoglyceride (DALG), and epoxidized soybean oil were added to prepare the feedstock. The content of methyl cellulose in the feed was adjusted to 403 ppm with respect to the sum of the mass of VD and VC. The amount of the above additives in the feedstock was adjusted so that the total amount of the additives would be 8.3 parts by mass with respect to 100 parts by mass of vinylidene chloride/vinyl chloride copolymer to be synthesized. A vinylidene chloride-based resin composition containing a vinylidene chloride/vinyl chloride copolymer was prepared by a suspension polymerization method using this raw material.

A vinylidene chloride resin composition was melt extruded through an annular die at 185° C. using a single screw extruder, and the resulting tubular parison was quenched with water and then heated to around room temperature in a hot water bath. After that, inflation biaxial stretching is performed at a stretching ratio of 4.1 times in the machine direction (MD) and 4.7 times in the transverse direction (TD), and further after relaxation in the MD at a relaxation rate of 11% in the machine direction (MD). , was taken up by a take-up roller. The wound film was slit and rewound to obtain a wound resin film-1 having a thickness of 10 μm, a width of 30 cm and a length of 50 m.

1-2. Production of resin film-2 A wound body was obtained in the same manner as in the production of resin film-1, except that the relaxation rate in the longitudinal direction (MD) was 12% when the vinylidene chloride resin composition was formed into a film. A resin film-2 was obtained.

1-3. Production of resin film-3 A wound body was obtained in the same manner as in the production of resin film-1, except that the relaxation rate in the machine direction (MD) was 9% when the vinylidene chloride resin composition was formed into a film. A resin film-3 was obtained.

1-4. Preparation of resin film-4 A vinylidene chloride resin obtained by setting the methyl cellulose additive to the raw material used for synthesis of the vinylidene chloride resin composition to 250 ppm with respect to the total amount of the mass of VD and VC. A wound resin film-4 was obtained in the same manner as the resin film-1 except that the relaxation rate in the machine direction (MD) was 9% when the composition was formed into a film.

1-5. Preparation of resin film-5 Liquid paraffin as a tackifier was added in an amount of 782 ppm with respect to the total amount of the mass of VD and VC to the raw materials used for synthesizing the vinylidene chloride resin composition. Resin film-5 in the form of a wound body was obtained in the same manner as resin film-4, except for the above.

1-6. Production of resin film-6 To the raw material used for synthesizing the vinylidene chloride resin composition, liquid paraffin was added in an amount of 782 ppm with respect to the total mass of VD and VC, and vinylidene chloride obtained. When the resin composition is made into a film, the stretching ratio in the longitudinal direction (MD) is 3.2 times, the stretching ratio in the transverse direction (TD) is 5.4 times, and the relaxation rate in the longitudinal direction (MD) is 10%. A wound resin film-6 was obtained in the same manner as the resin film-1 except that the resin film-1 was prepared.

1-7. Production of resin film-7 A vinylidene chloride resin obtained by setting the methyl cellulose additive to the raw material used in the synthesis of the vinylidene chloride resin composition to 755 ppm with respect to the total amount of the mass of VD and VC. A wound resin film-7 was obtained in the same manner as the resin film-1 except that the relaxation rate in the machine direction (MD) was 9% when the composition was formed into a film.

The amount of additives (water-soluble cellulose derivative and tackifier) used in the production of resin film-1 to resin film-7, and the production conditions (longitudinal direction (MD) draw ratio, transverse direction (TD) draw ratio , and the relaxation rate in the machine direction (MD)) are shown in Table 1.

2. Evaluation 2-1. Amount of Extracted Water-Soluble Cellulose Derivative Each of Resin Film-1 to Resin Film-7 having a sufficient length was pulled out from the roll and cut to obtain a test piece.

The test piece was immersed in 100 ml of ethanol, heated to 70° C., and extracted for 5 hours. After that, the extract was dried to obtain an ethanol extract. The above ethanol extract was dissolved in 15% aqueous ethanol solution and washed with carbon disulfide. After washing, the aqueous phase was dried and iodomethane produced by reaction with hydrogen iodide (HI) was dissolved in o-xylene.

The iodomethane-dissolved o-xylene layer was analyzed by gas chromatography (GC), and the amount of iodomethane obtained was converted to the amount of methyl cellulose to obtain the amount of methyl cellulose eluted from the surface of the resin film. The obtained amount of methyl cellulose was divided by the area of the resin film (unit: m ² ) to obtain the amount of water-soluble cellulose derivative present on the surface of the resin film (unit: μg/m ² ).

GC was performed using the following equipment and conditions.
(Measuring equipment/column)
GC-FID: GL sciences GC-4000 Plus
Column: Agilent J&W GC column DB-624
(Length: 30m, ID: 0.530mm, Film: 3.00μm)
(GC conditions)
Column temperature: 60°C (held for 5 minutes) → temperature increase 20°C/min → 210°C (held for 5 minutes)
Inlet temperature: 230°C
Detector temperature: 230°C
Carrier gas: N ₂ (column flow rate 4.2 ml/min)
Injection Method: Split (5:1)
Injection volume: 1 μl

2-2. Surface Adhesion Strength Each of Resin Film-1 to Resin Film-7 was pulled out from the roll and cut into a size of 200 to 300 mm in the length direction (MD)×300 mm in the width direction (TD) to obtain a test piece.

Two aluminum cylindrical jigs with a bottom area of 25 cm ² and a mass of 300 g were prepared. Each test piece was fixed to the bottom surface of one of the jigs while being tensioned so as not to form wrinkles. A test piece obtained from the same resin film was also fixed to the bottom surface of the other jig while being tensioned so as not to form wrinkles. These two jigs were brought into contact with each other in the vertical direction so that the bottom surfaces to which the test pieces were fixed completely overlapped, and the jig on the vertically upper side was pressed by its own weight for 1 minute to crimp the test pieces together. Subsequently, using Tensilon RTC-1210A, which is a tensile compression tester manufactured by Orientec Co., Ltd., the two jigs are pulled in opposite directions (vertical direction) at a speed of 100 mm / min, and the jig (test The maximum load (unit: N) for peeling off the test piece was taken as the surface peel strength of the test piece. The measurement was performed in an atmosphere of 23° C. and 50% RH, and the average value of the surface peel strengths obtained for five test pieces was taken as the surface adhesive strength of the resin film.

2-3. Tear strength to MD Pull out each of the resin film-1 to resin film-7 from the winding body, cut it to a size of 63.5 mm in the length direction (MD) × 50 mm in the width direction (TD), and use it as a test piece. did.

No. 1, which is a light load tear tester manufactured by Toyo Seiki Seisakusho Co., Ltd. 193 Model D was used, and the measurement range was set to 196 mN, and the tear strength to MD of each test piece was determined. After setting the test piece in the center of the clamp, cut with a knife at the center of the test piece in the width direction (TD) so that the cut length in the length direction (MD) is 12.7 mm, and swing the pendulum was opened to measure the maximum load (unit: mN) for tearing the test piece. The measurement was performed in an atmosphere of 23° C. and 50% RH, and the average value of the MD tear strength obtained for five test pieces was taken as the MD tear strength of the resin film.

2-4. Haze Value Each of Resin Film-1 to Resin Film-7 having a sufficient length was pulled out from the roll and cut to obtain a test piece.

Using a haze meter NDH7000SP manufactured by Nippon Denshoku Industries Co., Ltd., the haze value (unit: %) of each test piece was measured according to JIS K 7136 (2000). The average value of the haze values obtained for the five test pieces was taken as the haze value of the resin film.

2-5. Puncture Strength Each resin film-1 to resin film-7 having a sufficient length was pulled out from the roll and cut to obtain a test piece.

Using a tensile tester TENSILON RTG-1210 manufactured by A&D Co., Ltd., the puncture strength (unit: N) of each test piece was measured according to JIS Z 1707 (2019). The measurement was performed in an atmosphere of 23° C. and 50% RH, and the average value of the puncture strength obtained for five test pieces was taken as the puncture strength of the resin film.

2-6. Restoration time Each resin film-1 to resin film-7 was stored in a storage box (manufactured by Kureha Co., Ltd., a storage box for Kurewrap), extended 30 cm from the storage box, and with the lid tightly closed, the blade Each resin film was cut so that the mold remained on the resin film. After that, the remaining resin film was rewound inside the container while avoiding wrinkles as much as possible, and the ends of the resin film were brought into close contact with the wound resin film.

From this state, 40 evaluators, including men and women, were asked to pull out the entire width of the resin film to the outside of the storage box without using tools such as tape so as not to cause tearing in the longitudinal direction (MD). The time from when the evaluator found the end of the resin film in close contact with the wound resin film to when the entire width of the resin film was pulled out of the storage box was measured and used as the recovery time. The measurement was performed in an atmosphere of 23° C. and 50% RH, and the average value of the recovery times obtained in five tests was taken as the recovery time of the resin film.

Resin film-1 to resin film-7, the above-mentioned surface adhesion, tear strength to MD, ratio of surface adhesion to MD tear strength (surface adhesion / tear strength to MD), puncture strength, Table 2 shows the evaluation results of the recovery time and the recovery time. In Table 2, "-" indicates that evaluation was not performed.

As is clear from Table 2, the ratio of the surface adhesion value (N) to the MD tear strength value (mN) is 0.35 or more and less than 0.41 Resin Film-1 and Resin Film- 2 had a remarkably shorter recovery time from the unwound state than Resin Film-3 to Resin Film-5.

Further, as is clear from Table 1, such resin film-1 and resin film-2 contain a monomer for synthesizing a vinylidene chloride resin by polymerization, and the content of the total mass of the monomer is is 300 ppm or more and 600 ppm or less, using a resin composition obtained by suspension polymerization in an aqueous medium, the resin composition melted and extruded is stretched to the MD. is 3.5 times or more and 5.0 times or less, the stretching ratio to TD is 4.0 times or more and 5.5 times or less, and the relaxation rate to MD is 10.0% or more and 12.5% It was manufactured by a method of relaxing as follows.

The resin film of the present invention is easy to peel off the end portion from the wound portion in the unwound state without tearing the resin film in the longitudinal direction. Therefore, the resin film of the present invention can be suitably used in various applications such as home use, laboratory use and industrial use.

Claims (5)

A resin film made of a vinylidene chloride resin composition,
The ratio of the surface adhesion value (unit: N) to the MD tear strength value (unit: mN) (surface adhesion value / tear strength value to MD) is 0.35 or more and 0.41 is less than
resin film. The value of the tear strength to the MD is 32.0 mN or more and 34.5 mN or less,
The surface adhesion value is 12.0 N or more and 13.0 N or less,
The resin film according to claim 1. 3. The resin film according to claim 1, which has a haze value of 1.2% or less. The resin film according to any one of claims 1 to 3, which has a puncture strength value of less than 4.0N. A method for producing a resin film, comprising: stretching a melted and extruded vinylidene chloride resin composition; and relaxing the stretched vinylidene chloride resin composition,
The vinylidene chloride resin composition contains a monomer for synthesizing a vinylidene chloride resin by polymerization in the presence of a water-soluble cellulose derivative having a content of 300 ppm or more and 600 ppm or less with respect to the total mass of the monomer. A resin composition obtained by suspension polymerization in an aqueous medium,
In the stretching step, the vinylidene chloride-based resin composition is stretched so that the stretching ratio in the MD is 3.5 times or more and 5.0 times or less, and the stretching ratio in the TD is 4.0 times or more and 5.5 times or less. stretched to
In the relaxing step, the stretched vinylidene chloride resin composition is relaxed so that the relaxation rate to MD is 9.5% or more and 12.5% or less.
A method for producing a resin film.