JPH11157573A - Packaging stretch-film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable breadthwise smooth stretching with a stretching machine. SOLUTION: A roll 1 is unrolled, and edges on both sides in the longitudinal direction are held between endless belts of holding devices 3 and 4 constructed of paired upper and lower endless belts, and breadthwise stretching is made to make up a packaging stretch film for packaging. The film is made of polyvinyl chloride mixed with antifogging agent, and film unrolling force is 200-500 g per 350 mm film width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stretch film for packaging. More particularly, the present invention relates to a wrap film suitable for being stretched in the width direction by an extender during use.

[0002]

BACKGROUND OF THE INVENTION Stretch films for packaging made of thermoplastic resins such as polyvinyl chloride, polyvinylidene chloride and polyethylene are used for various purposes such as food packaging. A typical example is tray packaging, which is frequently used in supermarkets and convenience stores. This tray packaging is a packaging method in which foods such as fish and meat are put in a tray container and covered with a stretch film from above. The stretch film used here is wound on a roll. Then, the roll is set on a sheet breaking machine, and the stretch film is pulled out from the roll and used for coating the tray container.

[0003] By the way, the length and width of tray containers vary depending on the type of food to be stored. The stretch film is selected and used according to the length of the tray container. Therefore, it is necessary to prepare various types of stretch film rolls having different widths, and each time the length of the tray container to be coated changes, it is necessary to change the stretch film rolls corresponding to the length of the tray container. Therefore, the packaging of the tray container has the trouble and trouble of changing rolls outside the packaging operation. In order to reduce such inconvenience and labor, it has been proposed to stretch a stretch film drawn from a reverser in the width direction in accordance with the length of the tray container and provide the stretched film to cover the tray container (Japanese Unexamined Patent Application Publication No. Hei 8 (1996)). 2170
08 publication).

[0004] As one of stretchers for stretching the above stretch film in the width direction, both side edges in the length direction are sandwiched by grippers comprising a pair of upper and lower endless belts, respectively.
Machines for stretching in the width direction have been proposed. Then
When the stretching machine is wrapped with a conventional stretch film for packaging, the stretch film may fall out from between the endless belts of the gripper at the time of stretching, and the stretching operation may not be performed. An object of the present invention is to provide a stretch film that can be smoothly stretched by the above-described stretching machine.

[0005]

Means for Solving the Problems The inventors of the present invention have made various investigations on the cause of the stretch film coming off from between grippers such as an endless belt when stretched in the width direction by using the above stretching machine. It was found that the antifogging agent incorporated had an effect. That is, the antifogging agent blended in the packaging stretch film collects on the film surface, and this antifogging agent affects the lubricity of the film and makes it easy to slip out of a gripping tool such as a polyurethane endless belt during the above stretching. I figured it out. By the way, when I tried using a polyvinyl chloride film that does not contain an antifogging agent, the film did not come off from grippers such as endless belts at the time of the above stretching, but it was released from the roll and the film was pulled out. It required an extraordinarily large amount of power and could not work smoothly. As a result of various studies, the present inventors have found that the force required to release the film from the roll, that is, the release force is 2 mm per 350 mm film width.
It is found that the film having a thickness of 100 to 500 g can be smoothly delaminated, and can prevent the endless belt from coming off the gripper during stretching, and that the delamination force varies depending on the type and amount of the antifogging agent. Thus, the present invention has been completed.

That is, the present invention relates to a packaging for use in packaging by unwinding and pulling out from a roll, and then holding both side edges in the length direction with a pair of endless belts or the like and stretching in the width direction. Stretch film, comprising a polyvinyl chloride film containing an anti-fogging agent, wherein the repulsive force of the film is 2 per 350 mm of the film width.
It is a stretch film for packaging characterized by being 100-500 g.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The material of the stretch film for packaging of the present invention is polyvinyl chloride or a copolymer with another copolymerizable vinyl monomer mainly containing vinyl chloride.
Further, an antifogging agent is added to the stretch film for packaging in order to prevent water droplets from adhering to the film surface. In addition, if necessary, a plasticizer, a stabilizer, an antibacterial agent and the like are added. This polyvinyl chloride film is extruded,
It can be formed by calendering or the like. The thickness of the film is about 7 to 20 μm.

The use of the packaging stretch film of the present invention will be described. In the present invention, the polyvinyl chloride film of the stretch film for packaging is applied to the stretching machine,
Stretch and use according to the length of the tray container. FIG.
(A), (b) and (c) of FIG. 1 show an example of a stretching process using an extender. 1 is a roll of a polyvinyl chloride film. 2 is a mandrel supporting this roll. Reference numerals 3 and 4 denote a pair of grippers for gripping both side edges in the longitudinal direction of the film. This gripper 3, 4
Are made up of a pair of upper and lower endless belts that rotate in opposite directions. The upper and lower endless belts grip and transport both ends of the film. Further, the distance between the pair of grippers can be increased.

The stretch film for packaging of the present invention
As shown in FIG. 1 (a), a roll of a polyvinyl chloride film in a roll shape is set on a reversing machine (not shown), and the leading end 5 of the film is pulled out.
4 respectively. The film is transported forward while being held by the holding machine, that is, while being held between the endless belts. Then, cutting 6 is performed according to the length of the tray container. FIG. 1B shows a state in which the film 7 to be used is accommodated in the grippers 3 and 4. In this state, the rotation of each endless belt of the gripper is stopped. Next, as shown in FIG. 1C, the distance between the grippers is gradually increased. Thereby, the film 7 is stretched in the width direction to have a required width. The film 7 shown in FIG.
Is stretched, the tray container storing the product is lifted from below to cover the tray. Thus,
Narrower films can be used to coat larger length tray containers. In addition to the above example, the stretching machine grips both side edges of the film unwound from the reverser with a pair of inverted C-shaped grippers, and gradually stretches the film to a required width while transporting it. Machine can be used.

At the time of the stretching operation in the above-mentioned stretching machine,
In particular, when the film is stretched in the width direction while gradually increasing the distance between the pair of grippers, both side edges of the film may come off from between the endless belts that sandwich the film. The present invention
The repulsive force of the film is 200 per 350 mm
To 500 g, preferably 230 to 400 g, and more preferably 250 to 350 g. If the repulsive force is less than 200 g, it will easily come off from a gripper such as an endless belt during the above stretching, and if it exceeds 500 g, the roll will not be released smoothly. The stretch film for packaging of the present invention is particularly suitable when the endless belt made of polyurethane is stretched in the width direction by an extender using a gripper.

The method for measuring the reaction force in the present invention is as follows. That is, as described with reference to FIG. 2, a roll 1 on which a polyvinyl chloride film having a width of 350 mm is wound.
The mandrel 1 is passed through a mandrel, and the mandrel is set on the reversing machine 12 in such a manner that the mandrel can freely rotate around the shaft. One end of the film is pulled out from the roll, and the entire end of the film is gripped by the gripper 14 of the gripper 13, and one end of the film is fixed to the gripper 13. The knob 13 is fixed to the fixed wall 15 via the load cell 16.
Hang it on. Then, the unraveling machine 12 is placed on the table 17 which can be dropped at a predetermined speed along the side walls 18 and 19, and the table is dropped. The film on the roll is unraveled by the drop of the table. Then, the stress applied at the time of this disassembly is measured with a load meter. Using an autograph (strograph) type tensile tester as a load meter, measurement is performed by dropping at a speed of 500 mm / min. The change with time of the tensile strength applied at the time of this dissolution is charted. The disintegration starts when a certain tension is applied, and once the disintegration starts, the strength of the tension appears over time. If this is shown in a graph, it will be a curve having continuous peaks and valleys. In the present invention, the value at the time when the tension is increased during the drawing (removing) by 500 mm, that is, the average value of the vertexes of each peak of the graph is defined as the repelling force. When the roll width is not 350 mm, the roll width is 350 mm after measurement.
Convert to width.

The packaging film of the present invention contains an antifogging agent. The repulsive force can be adjusted by the type and amount of the antifogging agent. Traditionally used normally,
The repulsive force of a polyvinyl chloride film in which a glycerin fatty acid ester-based antifogging agent is blended in a usual amount is a film width of 35.
It is 120 g or more and less than 200 g per 0 mm. As long as the polyvinyl chloride film is used as a normal stretch film for packaging, there is no problem. However, it is not suitable for stretching in the width direction at the time of packaging because the polyvinyl chloride film is easily pulled out from between the endless belts of the extender. Reducing the amount of antifogging agent can increase the repulsive force, but if the amount is reduced too much, it becomes an unqualified film that does not have the antifogging performance that packaging films must have. I will. In addition, there is a possibility that it may not be able to be pulled out smoothly from the crusher during use.

The antifogging agent used in the present invention includes glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, and the like. ,
Sorbitan monolaurate, sorbitan monooleate,
Sorbitan sesquiolate, polyoxyethylene sorbitan monolaurate, di- (2-hydroxyethyl) alkylamine, polyoxyethylene alkyl ether and the like. The glycerin fatty acid ester-based anti-fog agent gives the film slipperiness and imparts the property of reducing the repulsive force, while the sorbitan fatty acid ester-based, polyoxyethylene sorbitan fatty acid ester-based, and fatty acid alkylolamide-based anti-fog agents are provided. The fogging agent has the property of giving the film less slipperiness and increasing the repulsive force. Therefore, by appropriately mixing these, the repulsive force can be reduced to a film width of 3 mm.
The weight can be 200 to 500 g per 50 mm.
In addition, a required amount of antifogging agent can be added. Stretch film of the present invention, the above-mentioned thermoplastic resin antifogging agent,
In addition, plasticizers, stabilizers, antibacterial agents, etc. are blended as necessary,
It is molded by a usual method such as extrusion molding.

[0014]

EXAMPLES AND COMPARATIVE EXAMPLES Examples 1-2 and Comparative Examples 1-2 Plasticizer (DINA) 35 was added to 100 parts by weight of polyvinyl chloride.
Parts by weight, epoxy soybean oil 15 parts by weight, stabilizer (Ca-Z
n-type) 1.0 part by weight and various antifogging agents of the following (1) to (4) were compounded in the following amounts, kneaded, and extruded to form a film having a thickness of 13 μm. This film was cut into a width of 350 mm and wound up on a roll to form a roll of a stretch film. The roll reaction force of this roll was measured using a testing machine shown in FIG.

(1) When 0.8 parts by weight of sorbitan laurate and 0.8 parts by weight of polyoxyethylene alkyl ether were used as the antifogging agent, the repulsive force was 280 g (Example 1). (2) When 0.7 parts by weight of sorbitan laurate, 0.7 parts by weight of polyoxyethylene alkyl ether and 0.2 parts by weight of diglycerin oleate are used as the antifogging agent,
The reaction force was 270 g (Example 2). (3) As antifogging agents, 0.4 parts by weight of polyoxyethylene alkyl ether, 0.6 parts by weight of diglycerin oleate, 0.4 parts by weight of diglycerin laurate, and 0.2 parts by weight of glycerin monooleate were used. The reaction force is 180
g (Comparative Example 1). (4) When 0.6 parts by weight of sorbitan laurate and 0.6 parts by weight of polyoxyethylene alkyl ether were used as the antifogging agent, the repulsive force was 550 g (Comparative Example 2).

The rolls of the stretch films of Examples 1 and 2 and Comparative Examples 1 and 2 were set on a rewinding machine as shown in FIG. 1 and pulled out from the rewinding machine and set on a stretching machine. The edge was sandwiched between a pair of upper and lower endless belts made of polyurethane and stretched in the width direction. In Examples 1 and 2, both the unraveling step and the stretching step could be performed smoothly, but in Comparative Example 1, both side edges of the film came off from between the endless belts during the stretching step, which hindered the stretching step. In Comparative Example 2, the feeding from the roll was not smooth, and there was a problem in use.

[0017]

The stretch film for packaging of the present invention is
At the time of use of the packaging, the operation of stretching in the width direction with the extender while unwinding from the roll can be performed smoothly. That is, when the stretcher grasps both ears of the film and stretches the film in the width direction, the film does not come off from a grasping tool such as an endless belt of the stretcher, and the film can be released smoothly. In addition, the antifogging agent can be used in a compounding amount that does not impair its effect.

[Brief description of the drawings]

FIG. 1 is a process diagram of stretching a stretch film for packaging of the present invention with an extender.

FIG. 2 Measurement device for reaction force

[Explanation of symbols]

1 roll of packaging stretch film, 2 mandrel,
3, 4 gripper, 5 film to be used, 11 roll of stretch film for packaging, 12 release machine, 13 gripper, 14 gripper, 16 load cell, 17 drop table

Claims (1)

[Claims] 1. A packaging stretch film for use in packaging by releasing the roll from the roll, and then pulling each side edge in the longitudinal direction with a pair of endless belts or the like and stretching it in the width direction. A stretch film for packaging, comprising a polyvinyl chloride film blended with an anti-fogging agent, wherein the repulsive force of the film is 200 to 500 g per 350 mm in film width.