JP2938181B2 - Packing stretch-wrap film and easily unsealable stretch-wrap package - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a stretch film for packaging and an easily-openable stretch package, and more particularly to a package which is easy to cut in a direction perpendicular to a film flow direction (lateral direction). The present invention relates to a stretch film for use and an easily openable stretch package which easily tears in one direction.

[Conventional technology]

There are various types of stretch films for packaging, such as those made of vinyl chloride resin, polyvinylidene chloride, and polyethylene. Among them, those made of vinyl chloride resin have transparency, flexibility,
Excellent antifogging property, food preservability, packaging suitability, self-adhesion, etc.
Meat at home and supermarkets, shops, restaurants, etc.
It is used in large quantities for packaging foods such as fresh fish, fruits and vegetables, side dishes, and home delivery dishes.

As a method of cutting this stretch film for packaging, a method of attaching a saw blade to an outer box of the stretch film for packaging and using it to cut the film or a method of fusing the film with a hot wire (commercially available as a handler Are). In particular, a method of attaching a saw blade to an outer box of a stretch film for packaging and cutting the film by using the saw blade is widely used at home. However, this saw blade is very dangerous when cutting the film, as it may hurt the hand.

In addition, since a film made of a vinyl chloride resin is hard to cut in the horizontal direction, depending on the type of saw blade, the film may be torn diagonally when cutting the film, or a considerably strong force may be required.

To open a package wrapped with a conventional soft vinyl chloride resin stretch film, peel off the film by holding the edge of the film located at the bottom of the tray, or insert your finger into the film stretched on the top surface of the tray. The film was forcibly torn.

However, when peeling the film by holding the edge of the film located at the bottom of the tray, it is difficult to hold the edge of the film because the film is soft and thin, and when peeling, it is difficult to peel and it takes a lot of labor and time. Cost me. Also, when a finger is inserted into the film stretched on the upper surface of the tray to forcibly tear the film, since the film is difficult to tear, excessive force is applied to impair the shape of the article, or the hand may be overpowered. Had the problem of touching and dirtying his hands.

As means for solving the above problems, for example, Japanese Patent Publication No. 42-22
No. 320 and Japanese Patent Publication No. 46-33799. The stretch film for food packaging produced by this method is obtained by forming a soft vinyl chloride resin film and then stretching the film at a temperature equal to or higher than the glass transition point in the film flow direction. Direction), and the package wrapped with the film can easily tear the film, and the article can be easily taken out.

However, since the stretch film for food packaging made by this method has a large shrinkage in the film flow direction, when the film is made into a roll, the end face is misaligned, the appearance of the roll is deteriorated, and the end face becomes uneven, so automatic packaging is performed. There is a problem that the film meanders and cannot be packaged when used in a machine. In addition, when packaging goods using trays, the film after packaging may have wrinkles, or if the package needs to be kept warm or exposed to high temperatures, the film may shrink, causing the tray to deform or collapse. There was a problem.

[Problems to be solved by the invention]

The purpose of the present invention is that the shrinkage in the film flow direction is appropriate,
Another object of the present invention is to provide a stretch film for packaging that can be easily cut in the lateral direction, and an easily-openable stretch package body that can tear the film easily and can take out articles smoothly.

[Means for solving the problem]

The present inventors have conducted intensive studies to achieve the above object, and as a result, completed the present invention.

That is, the present invention relates to a stretch film for packaging a soft vinyl chloride resin, wherein the shrinkage in the film flow direction is reduced.
5-25% at 60 ° C., and the Elementeldorf tear strength in the direction perpendicular to the flow direction of the film at 20 ° C.
A stretch film for packaging characterized by being 2 to 30 gf, and an easily-openable stretch package which wraps an article with the film and is easily tearable in one direction.

The soft vinyl chloride-based resin stretch film of the present invention can be obtained by blending a plasticizer and other optional additives to the vinyl chloride-based resin, mixing and molding.

As the vinyl chloride resin used in the present invention, not only polyvinyl chloride but also a copolymer containing vinyl chloride as a main component can be used. Examples of monomers that can be copolymerized with vinyl chloride include ethylene, propylene, acrylonitrile, vinyl acetate, maleic acid, itaconic acid, acrylic acid, methacrylic acid, and the like.

Examples of the plasticizer used in the present invention and other additives to be added as required include “Self-regulatory Standards for Vinyl Chloride Resin Food Packaging and the like” published by the PVC Food Sanitation Council (19).
Published in 1989, PL Standard Revision 9th Edition), and any material used for food packaging can be used.
Examples of plasticizers that are preferable to this standard include diisobutyl adipate, dinormal hexyl adipate, dinormal heptyl adipate, diisoheptyl adipate, dinormal octyl adipate, dinormalonyl adipate, diisononyl adipate, and adipate. Fatty dibasic esters such as dinormaldecyl, diisodecyl adipate, dinormal butyl sebacate, dinormal octyl sebacate, di-2-ethylhexyl adipate, dinormal hexyl azelate, and di-2-ethylhexyl azelate Plasticizer, tartaric acid diester,
Hydroxy polycarboxylic acid ester plasticizers such as acetyl triethyl citrate, acetyl tributyl citrate, acetyl tri-2-ethylhexyl citrate, tributyl citrate, monostearyl citrate, distearyl citrate and tristearyl citrate, acetyl Methyl ricinoleate, ethyl palmitate, ethyl stearate,
Fatty acid ester plasticizers such as normal butyl stearate, amyl stearate, cyclohexyl stearate, butyl oleate, hydrogenated rosin methyl ester, glycerin triacetate, glycerin tripiolate, glycerin tributyrate, glycerin triheptanoate, triglyceride Polyhydric alcohol fatty acid ester plasticizers such as methylene glycol dicaprylate, trimethylene glycol dicaprate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, epoxidized soybean oil, epoxidized castor oil Epoxidized linseed oil, epoxidized safflower oil, epoxidized linseed oil fatty acid butyl,
Epoxy plasticizers such as octyl epoxystearate, 3- (2-xenoxy) -1,2 epoxypropane, poly (propylene glycol, adipic acid) ester, poly (1,3-butanediol, adipic acid) ester, poly (Propylene glycol, sebacic acid) ester, poly (1,3-butanediol, sebacic acid) ester, poly (propylene glycol, phthalic acid) ester, poly (1,3-butanediol, phthalic acid) ester, poly (propylene) And polyester-based plasticizers such as glycol, adipic acid) ester, poly (1,6-hexanediol, adipic acid) ester, and acetylated poly (butanediol, adipic acid) ester. Used in combination of more than one species. Preferably, an epoxy plasticizer and another plasticizer are used in combination.

The use amount of the plasticizer is usually within 60 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight of the vinyl chloride resin.

Additives to be added as necessary include a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a coloring agent, an antifogging agent and the like.

The method for producing a stretch film for packaging a soft vinyl chloride resin of the present invention comprises mixing a plasticizer and other additives to be added to the above vinyl chloride resin with a known mixer such as a Henschel mixer. A film having a thickness of 15 to 100 μm is formed by a known extrusion molding method, and then the film is preheated to 50 to 120 ° C. by a known roll stretching method, and 1.5 to 5.0 times in the flow direction, preferably 2.0 to After stretching 4.0 times, it is obtained by heat setting at 80 to 120 ° C.

If the temperature at the time of stretching is lower than 50 ° C, the film will be broken, and if the temperature exceeds 120 ° C, the film will be wound around the stretching rolls, resulting in poor film forming workability. No tear strength is obtained.

If the stretching ratio is less than 1.5 times, sufficient stretching cannot be performed, so that the target Elmendorf tear strength cannot be obtained. If the stretching ratio exceeds 5.0 times, the film is broken and a product cannot be obtained.

If the heat setting temperature is less than 80 ° C, the shrinkage in the film flow direction will be larger than the target value, and if it exceeds 120 ° C, the film will be wound around the heat setting roll and the workability of film formation will worsen, even if the film can be formed. However, the desired shrinkage cannot be obtained.

The soft vinyl chloride-based resin stretch film of the present invention obtained by the above method has a shrinkage in the flow direction at 60 ° C. of 5 to 25%, preferably 10 to 20%. Moreover, it is easy to tear in the direction perpendicular to the flow direction, and the Elementeldorf tear strength is in the range of 2 to 30 gf, preferably 4 to 20 gf at 20 ° C.

If the shrinkage is less than 5%, the film will not be stretched and bend when packaging the article using the tray, and the packaging will not be successful. If the shrinkage exceeds 25%, the shrinkage in the film flow direction increases, and when the film is rolled, the end face shifts and the appearance of the roll deteriorates, and the end face becomes irregular. The film meanders when used and cannot be packaged. In addition, when articles are packaged using a tray, the packaged film becomes wrinkled, or when the package needs to be kept warm or is exposed to high temperatures, the film shrinks and the tray is deformed or crushed.

When the Elmendorf tear strength is less than 2 gf, the film is torn even by a small impact, and does not function as a package. On the other hand, if it exceeds 30 gf, the film becomes difficult to tear and the opening operation becomes difficult.

When the heat setting temperature is high, the shrinkage is small, and when the heat setting temperature is low, the shrinkage is high. When the stretching temperature and the stretching ratio are high, the Elmendorf tear strength decreases, and when the stretching temperature and the stretching ratio are low, the Elmendorf tear strength increases. Thus, the shrinkage ratio and the Elmendorf are determined by variously combining the heat setting temperature, the stretching temperature, and the stretching ratio. The tear strength can be adjusted.

The package of the present invention, using the soft vinyl chloride resin stretch film obtained by the above method, a manual packaging machine used when packaging with a normal stretch film,
Obtained by packaging with an automatic packaging machine or the like.

Notches, labels, or perforations may be added to the film to further facilitate tearing.

The package of the present invention can be applied not only to a package using a tray but also to a general stretch package such as a cardboard box or a can.

The material of the tray used as needed for the package of the present invention includes, for example, olefin resins such as polyethylene and polypropylene, polystyrene, vinyl chloride resin, acrylic resin, paper, and wood, but the material is limited. Not done. Further, the shape, size, and the like can be appropriately selected as needed.

In addition, the article to be used is not limited to food, and can be used widely, for example, tobacco, tissue paper, plastic model, etc., and the use is not limited.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

Examples 1 to 11, Comparative Examples 1 to 6 A vinyl chloride resin, a plasticizer and other additives
After mixing using a Henschel mixer at the mixing ratio shown in the table, the mixture was kneaded with an extruder and melt-extruded from a T-die at 200 ° C. to obtain a film having a thickness shown in Table 2. The obtained film was stretched in the film flow direction at the stretching temperature, stretching ratio and heat setting temperature shown in Table 2 to obtain a film having the thickness, Elmendorf tear strength and shrinkage shown in Table 2.

The obtained film is packed with a polystyrene tray using a commercially available handler, and the state of wrinkles generated during the preparation of the package, and the obtained package is placed in an oven maintained at 60 ° C. for 1 hour to deform the tray. The condition was visually evaluated. In addition, insert your finger into the film stretched on the top of the tray and open it,
The openability was evaluated. Table 2 shows the above results.

Physical property measurement method (1) Elmendorf tear strength Measured according to JIS P8116.

(2) Shrinkage The film was immersed in water at 60 ° C. for 1 minute and calculated by the following calculation method.

A: Length of original film B: Length of film after immersion for 1 minute (Effect of the Invention) The stretch film for packaging and the stretch package of the present invention have the following effects as apparent from the above examples. There is.

Since the film has a specific shrinkage ratio, when the film is made into a roll, the end faces are aligned, so that the appearance of the roll is improved, and even when used in an automatic packaging machine, the film does not meander, and the packaging workability is improved. Is improved.

The film prevents wrinkles from occurring in the film after packaging when the article is packaged using a tray.

Since the film has a specific tear strength, when packaging, without using a dangerous saw blade for cutting the film, it can be easily cut straight in the horizontal direction, and packaging with the minimum necessary film is possible. it can.

When cutting the film using a saw blade, regardless of the material and shape of the saw blade, the film can be easily cut only by applying light force, and it is safe without accidentally damaging the hand with the saw blade. is there.

The tray does not deform or collapse when the package needs to be kept warm or is exposed to high temperatures.

Since the film is easily torn, the package is easy to open and to take out the article. In particular, when a lunch box or the like is wrapped and heated in a microwave oven, it is much easier to open than a conventional stretch wrapper.

Since the stretch film for packaging and the stretch package of the present invention exhibiting the above effects are easy to handle, they greatly contribute to the distribution industry and end consumers.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B29K 105: 02 B29L 7:00 (56) References JP-A-60-187528 (JP, A) JP-A-59-213749 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 55/02-55/28 B29C 61/06-61/10 C08J 5/18 CEV C08L 27/06

Claims (2)

(57) [Claims] 1. A stretch film for packaging of a soft vinyl chloride resin, wherein the shrinkage in the film flow direction is 5 to 25% at 60 ° C., and the Elmendorf tear strength in the direction perpendicular to the film flow direction is 20. In ° C, 2-30 gf
A stretch film for packaging, characterized in that: 2. An easily-openable stretch package, wherein the stretch film for packaging according to claim 1 easily wraps the article in one direction.