JPH07112512A - Film for stretch packaging and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a stretch film with a polyolefin surface layer with good packaging properties in a stretch packaging machine and in parallel with an excellent balance in such characteristics as non-fogging properties, heat-sealing properties, label adhesiveness and optical characteristics. CONSTITUTION:A film for stretch packaging which is a film with the sum of loadings at 200% elongation in the longitudinal and transverse directions of at most 1,500g/cm width and wherein at least one of the surfaces of the film is a layer consisting of a polyolefin resin and on part of one of the surfaces of the film, 0.3-50mg/m<2> silicone oil and 0.5-50mg/m<2> anti-fogging agent are provided and a method for manufacture thereof is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch packaging film and a method for producing the same. In particular, it is suitable for food tray packaging and Nootley packaging, and has excellent packaging machine suitability such as slipperiness, heat sealability, and adhesion, and also has excellent label adhesion, antifogging properties, surface properties such as optical properties, and the like. The present invention relates to a film made of a well-balanced polyolefin resin as a raw material.

[0002]

2. Description of the Related Art Conventionally, for stretch packaging of food,
From the viewpoint of its price and film characteristics, especially excellent surface characteristics, mainly vinyl chloride or other copolymers,
A plasticized, for example, a vinyl chloride type stretch film containing 30 to 50% by volume of a plasticizer has been used. However, as is well known, these films have been pointed out to have environmental problems such as generation of hydrogen chloride gas during incineration and generation of harmful reaction products containing chlorine, and especially for food packaging. When used, it also had a hygienic problem that the contained plasticizer was easily transferred to food.

Polyolefin stretch films have been developed and put on the market as a means for solving the environmental and hygiene problems of such vinyl chloride stretch films. However, at present, the polyolefin stretch film as described above has not been widely used as a substitute for a vinyl chloride stretch film, despite its excellent environmental and hygienic properties.

As a cause for this, there is a price problem that it is generally more expensive than a PVC stretch film, but as a technical problem, a polyolefin stretch film is a so-called "machine" in a PVC stretch film specification packaging machine. The performance problem of poor "engagement" has not yet been fully resolved.

[0005]

For stretch wrapping using a vinyl chloride stretch film, a packaging machine developed exclusively for a vinyl chloride stretch film is used.
For example, most of the packaging machines for food packaging currently in operation in Japan are PVC stretch film packaging machines. A packaging machine for polyolefin stretch films has been developed, but the number of operating machines is still small. Therefore, in order to popularize the polyolefin stretch film, it was necessary to satisfactorily wrap it even with a vinyl chloride stretch film specification packaging machine.

However, when a polyolefin stretch film is used in a PVC stretch film specification packaging machine, there are cases where it cannot be satisfactorily packaged (hereinafter referred to as "mechanism improper"). For example, in order to wrap the film in the packaging machine, the film needs to be normally transported by a transport mechanism in the packaging machine. During the transportation,
The film must have good slidability with the "portion that needs to slide (such as the film pressing plate)" in the packaging machine, but conversely, "the part that needs to be in close contact with the film (belt for film transport, film transport) "Roll etc.)" requires sufficient adhesion. PVC stretch films had a seemingly well-balanced surface property of slipperiness and adhesion, but in general, polyolefin stretch films have a different balance of slipperiness and adhesion from PVC stretch films. When used in a wrapping machine developed for a stretch film, there were cases in which it could not be wrapped due to problems such as poor conveyance.

[0007] In particular, an example of a push-up type (elevator type) PVC stretch film packaging machine will be taken as an example to explain a general film transport mechanism in this packaging machine. The film is held by being brought into close contact with a rubber belt for transporting the film, and the film is transported by moving the rubber belt with the power of a motor or the like. Move while rubbing.

At that time, in the polyolefin stretch film, the front end of the film is rubbed against the film pressing plate and curled into a strand (hereinafter simply referred to as strand).
It is easy to cause a transport problem due to the film, and as a result, the film becomes insufficient in size, which causes a problem in packaging. According to the investigation by the inventors, in general tray packaging, if the length of the dimensional shortage of the film due to the twisting is about 40 mm or more, the packaging becomes defective, and it is best not to have it at all, but it occurs. Even if it is 20 mm or less, it has been proved that it can be packaged without any problem.

Further, in the case of a polyolefin stretch film, the film surface of the portion which is rubbed by the film pressing plate during transport is apt to be scratched due to melting due to frictional heat generated at that time, and particularly when it is severe, the film is There was a hole in the product, resulting in a finished package, and in particular the quality. On the other hand, the PVC-based stretch film had no such problems of twisting and scratching, although it was very tacky and flexible. Therefore, it has been necessary to solve transport troubles and scratches such as twisting of a polyolefin stretch film.

The cause of the transport trouble is mainly due to insufficient slipperiness of the film surface at the transport speed (rubbing speed of the film) of the film, and therefore, as a preventive measure, calcium carbonate or silica is generally used for the film. It is considered to add inorganic fine particles such as diatomaceous earth or a solid lubricant such as spherical silicone resin to improve the slip property of the film. As a report of an attempt to improve the slipperiness of a film by using a solid lubricant, for example, JP-A-60-12
There are 7367, JP-A-1-129050, JP-A-3-205440, and the like. But,
Even if these methods were tried, the mechanical easiness in the above-mentioned vinyl chloride stretch film specification packaging machine was not improved so much. In particular, not only is there little effect of suppressing this occurrence, but the adhesiveness (adhesion) of the film is too low, so
The film may unnecessarily easily come out of the film holder of the packaging machine during stretch wrapping, resulting in deterioration of wrapping property.

Further, since these methods are basically methods for improving the slipperiness by roughening the surface of the film by the presence of fine particles, the presence of particles may deteriorate the transparency of the film, or In particular, in the case of a thin film, holes may be formed in the film due to inorganic particles protruding from the film. The problem of opening holes in the film causes a problem of reduced productivity when the thin film is stretched and manufactured, and causes bubble puncture particularly in the inflation method. Further, in order to obtain a stretched thin film, a fine filter, generally a screen pack of about 250 mesh, is often used at the exit of the extruder. In that case, inorganic fine particles and the like are added. When a resin is used, there is also a problem that productivity is reduced due to clogging of the filter.

It is also considered that a lubricant is mixed with a resin and extruded to form a film, and then the lubricant is bleed from the inside of the film to improve the slipperiness of the film.
In this case, in many cases, the lubricant bleeds during the extrusion process and the raw material resin pellets slide on the screw, which often causes deterioration in extrusion stability. In particular, the more effective the lubricant is in improving the slipperiness of the film, the more likely it is for the screw to slip and the more difficult it is to knead.

Further, examples of using oils having poor antifogging property such as general silicone oils as lubricants are disclosed in JP-A-2-45366 and JP-A-5-39375.
There is JP-A-5-170958. In the methods of these publications, when the amount of silicone oil present on the film surface is too large, not only the adhesiveness is lowered, but also the antifogging property is reduced even if a sufficient amount of antifogging agent is added to the film. I also had the problem. Although the cause of the decrease in anti-fog property is not clear, the anti-fog property is poor due to the presence of a silicone oil film on the outer surface of the anti-fog agent present on the film surface due to the excessive amount of silicone oil. It is considered that the spots appear on the film surface.

As described above, there has been no polyolefin-based stretch film which has simultaneously solved mechanical characteristics of a PVC-based stretch film specification packaging machine and surface characteristics such as antifogging property. In view of such circumstances, the present invention is
An object of the present invention is to provide a polyolefin-based stretch film having a good balance between slipperiness and adhesion, good mechanical easiness, and excellent antifogging property, heat sealability, label adhesiveness, and optical properties in stretch packaging. .

[0015]

[Means for Solving the Problems] As a result of the research conducted by the inventors,
When a stretch film with a predetermined amount of silicone oil is used on a film formed by mixing a predetermined amount of anti-fog agent with the resin raw material and heating and melting with an extruder, it is possible to use a stretch wrapping machine with PVC. It has been found that the above-mentioned problems can be solved by satisfying both the anti-fog property and the anti-fogging property and the present invention has been accomplished.

That is, according to the present invention, the vertical and horizontal directions are 20.
A film having a total 0% elongation load of 1500 g / cm width or less, at least one surface of the film is a layer made of a polyolefin resin, and 0.3 to 50 mg / at least on one surface of at least a part of the film. is for stretch packaging film characterized in that arranged anti-fogging agent of the silicone oil and 0.5 to 50 mg / m ² of m ^2, and molded by heating and melting the resin material in an extruder, the anti-fogging agent A silicone emulsion is obtained by applying a silicone emulsion to one surface of a film raw material contained therein, stretching the film raw material in at least a uniaxial direction, and then bringing the silicone emulsion-coated surface of the stretched film into contact with a non-coated surface. Stretch characterized in that the silicone is also transferred to the non-coated surface and the silicone emulsion is placed on both sides of the film. It is a method of manufacturing a packaging film.

The present invention will be described in detail below. First, the polyolefin resin will be described. At least one surface of the film used in the present invention is a layer made of a polyolefin resin, but the type of resin is not particularly limited, and for example, the following resin group is preferably used.

That is, polyethylene (hereinafter PE), polypropylene (hereinafter PP), or a monomer selected from a vinyl ester monomer, an aliphatic unsaturated monocarboxylic acid, an aliphatic unsaturated monocarboxylic acid alkyl ester and ethylene. Copolymers or their derivatives, different α-olefins (other than ethylene), copolymers of the same, ethylene-α
Olefin copolymer (especially α-olefin has 3 to 3 carbon atoms)
12 are preferable, for example, butene-1, hexene-1, heptene-1, 4-methyl-1-pentene, octene-1, etc.), butyl rubber elastomer, styrene-butadiene elastomer (particularly thermoplastic block copolymer) Combined), crystalline polypropylene, crystalline polybutene-
Resins such as 1 (hereinafter PB-1) are used.

Above all, when it is used as a film for stretch packaging, it is used because the 200% elongation load in the longitudinal and transverse directions when the film is formed on the film needs to be adjusted within the scope of the claims of the present invention. A soft resin is often used as the polyolefin resin. The soft resin is a copolymer of ethylene with at least one monomer selected from PE, vinyl ester monomer, aliphatic unsaturated monocarboxylic acid, and aliphatic unsaturated monocarboxylic acid alkyl ester, or these Derivatives, copolymers of olefins (other than ethylene), ethylene-α-olefin copolymer elastomers (linear type VLDPE, ULDPE
And the like), and a butyl rubber elastomer, a styrene-butadiene elastomer, or the like may be used.

These resins may be used alone, but may be a copolymer or a mixed composition, and may contain a required amount of a plasticizer,
It may contain an anti-blocking agent, an antioxidant, an antistatic agent and the like. If necessary, a resin other than the above-mentioned polyolefin resins may be mixed, but even in that case, the above-mentioned polyolefin resin is contained in the surface layer in an amount of 70% by weight or more. Is preferred.

The film may be a single layer of polyolefin resin, or may be a multi-layer film in which one or more other resin layers are laminated. In the case of multiple layers, at least one surface of the film needs to be a layer of the above-mentioned polyolefin resin. Next, the silicone oil will be described.
The function of the silicone oil in the present invention does not impair surface properties such as anti-fogging property required for the stretch film, and improves the slipperiness of the film and the portion that needs to slip in the packaging machine as described above, It is to solve the problem of the damage of the saw and the film in the packaging machine.

The type of silicone oil used is not particularly limited, and may be selected depending on the application. For example, dimethyl silicone oil, methylphenyl silicone oil, polyether modified silicone oil,
A simple substance such as an alkyl-modified silicone oil or an amino-modified silicone oil may be used, or a mixture containing at least one of these oils is preferably used. The viscosity of the oil is not particularly limited, but an oil having an appropriate viscosity may be selected, for example, from the viewpoint of ease of application by the application method. Especially when used for food packaging, 100 to 100
It is preferably in the range of 0000 cs (centistokes).

When the silicone oil is applied to the film in the production method of the present invention, it is preferable to use a silicone emulsion. Silicone emulsion means the above-mentioned silicone oil, water, alcohols,
It is a macroemulsion, a miniemulsion, a microemulsion or the like with ethers and the like (hereinafter, the three are collectively referred to as an emulsion), and includes those containing an emulsifier such as a surfactant for stabilizing the emulsion.

Among the above, the preferred emulsion is a system mainly composed of silicone oil and water, and in this case, it is preferably an O / W type in which oil particles are dispersed in an aqueous phase. A macroemulsion as used herein generally has an average oil particle size of 0.4 μm or more, a miniemulsion has an oil particle size of about 0.1 to 0.4 μm, and a microemulsion generally has an oil particle size of about 0.01 to 0.1 μm. Refers to the dispersion system. Since macroemulsions and miniemulsions are generally thermodynamically unstable, non-ionic, anionic or cationic surfactants are usually added as a third component to stabilize the milky white. Is a liquid. On the other hand, microemulsions are generally more thermodynamically stable than macroemulsions and miniemulsions, and are generally transparent because the oil particles have a wavelength of visible light or less, which is preferable depending on the film manufacturing method and application.

Further, the emulsion is preferably stable, and for that purpose, an emulsion to which a nonionic or anionic or cationic surfactant is added may be used. In addition, in particular, an additional antifogging agent for assisting the antifogging property of the antifogging agent contained in the film, an inorganic lubricant such as silica fine particles or metal fine particles for further improving slipperiness, or an organic material such as a fine particle silicone resin. It is also possible to add a proper amount of a third component such as a lubricant. However, in the case of the addition of the third component and the like, the addition amount thereof is within a range that does not cause density unevenness and dispersion unevenness that cause coating unevenness, and particularly does not cause destabilization such as demulsification, and the film. It is necessary to be within a range that does not hinder the production of

The oil concentration in the emulsion is not particularly limited as long as the amount of oil finally attached to the film is within the range of the present invention. However, depending on the film forming method and coating method,
From the viewpoint of the stability of the emulsion and the ease of adjusting the coating amount, it is preferable to use an emulsion having an oil concentration of 0.1 to 50% by weight, more preferably 1 to 40% by weight.
If you use an emulsion with an excessively high concentration, the viscosity will be high, and coating unevenness will occur easily.On the other hand, if you use an emulsion with a too low concentration, you must increase the emulsion coating amount in order to adhere the required amount of oil to the film. This is also undesirable because it also causes uneven coating.

The coating amount of the above silicone oil on the film is 0.3 to 50 mg / m ² per coated surface of the film.
It is necessary to be 1 to 25 mg / m ² , more preferably ² to 15 mg / m ² . 0.3
When it is less than mg / m ^2, the slipperiness of the film becomes insufficient, and for example, the film is rolled into a twist in a packaging machine, which causes conveyance failure. On the other hand, when it is 50 mg / m ² or more, not only the antifogging effect of the antifogging agent coexisting on the film surface is hindered and the antifogging property is deteriorated, but also it is necessary to adhere to the film conveying belt, the film conveying roll and the like. In many cases, the adhesiveness becomes insufficient and the film cannot be conveyed.

The coating amount can be adjusted by adjusting the concentration of silicone oil in the silicone emulsion, or in the case of inflation film formation, the film stock or the film in the process.
A known method such as adjusting the pinch roll pressure for conveying the stretched film may be used. The antifogging agent will be described. In the present invention, it is necessary to add an antifogging agent in order to give the film antifogging properties. As the kind of the antifogging agent, nonionic surfactants such as polyhydric alcohol fatty acid esters and polyoxyethylene alkyl ethers and other effective agents may be used. They include, for example, diglycerin monoglyceride of oleic acid or lauric acid, sorbitan monolaurate, polyoxyethylene nonylphenyl ether, glyceride monooleic acid, alkyl alkylolamide, polyoxyethylene monooleate, and the like. Particularly preferred examples of the component include diglycerin-oleate such as diglycerin-monooleate and diglycerin-diolate, or diglycerin-laurate such as diglycerin-monolaurate and diglycerin-dilaurate, and diglycerin- Examples include diglycerin stearate such as monostearate and diglycerin-distearate, glycerin-monooleate, and glycerin-diolate. An appropriate material may be selected from these depending on the application, etc., and may be used singly or as a mixture.

The surface amount of the above antifogging agent is required to be 0.5 to 50 mg / m ² per coated surface of the film, preferably 1 to 35 mg / m ² , and more preferably 3 to 25 mg / m ² . ^{Is 2} . Surface amount is 0.5mg / m ²
If it is below 50%, the antifogging property is not sufficiently exerted, and it is 50 mg.
If it is / m ² or more, not only the slipperiness of the film due to silicone oil is hindered but also the film becomes sticky, which is not preferable.

The ratio of the coating amount of silicone oil to the surface amount of antifogging agent is preferably silicone oil / antifogging agent =
Within the range of 10/1 to 1/20, more preferably 5/1
It is better to be in the range of 1/10 to easily balance the slipperiness and the antifogging property. The above antifogging agent or silicone oil need not be placed on the entire surface of the film, and for example, when coating the film with a coater after forming the film, the antifogging agent is placed only on the part where antifogging property is required, The silicone oil may be provided only on the part where slipperiness is required. In that case, the amount of silicone oil applied and the amount of antifogging agent surface indicate the amount of adhesion only to the coating portion where the silicone oil and the antifogging agent are required.

A method of manufacturing the film will be described. The method for producing the film is, for example, a method in which a tubular film raw material extruded with a circular die is stretched by an inflation method, a film raw material extruded with a general T-die is uniaxially stretched, or a sequential or simultaneous biaxially stretching method is used. Is taken. The extrusion may be performed by one extruder or may be coextruded by a plurality of extruders to form a multilayer film.

In the production of the film of the present invention, it is necessary to heat and melt the resin raw material with an extruder to form a raw film of the film containing the antifogging agent. By doing so, the antifogging agent added after the film formation gradually bleeds onto the film surface, so that the thickness of the antifogging agent film can be easily made uniform.
Therefore, the antifogging property is exhibited at an excellent level, and the film is likely to be uniform over the entire surface. As an example of the method of incorporating the anti-fog agent into the raw film, the anti-fog agent may be kneaded into the resin raw material by in-line injection during the extrusion step,
Alternatively, a master batch resin pellet in which an antifogging agent is kneaded is prepared in advance, and this may be extruded to form a raw film.

The silicone oil is preferably applied by using the above-mentioned silicone emulsion. For example, in the case of extrusion by a circular die, when the tubular raw material of the molten film immediately after extrusion is water-cooled in a cooling water tank or the like. The silicone emulsion preferably adjusted by the above method is put in a tube and enclosed by a nip roll (hereinafter, the liquid enclosed in the tube of the tubular film between the nip rolls is called a sock liquid).
By doing so, it is applied to the inner surface of the tube-shaped film original fabric. Then, it is preferable to control the coating amount by adjusting the nip pressure of the nip rolls or the oil content concentration in the emulsion, and then to stretch by the inflation method, because it is possible to coat the silicone emulsion in a continuous uniform and thin film easily. .

In this case, the silicone emulsion may be applied to the outer surface of the raw material of the tubular film before stretching with a coater or the like, but contamination of rolls and the like due to silicone oil is a problem when passing through the manufacturing process. In such a case, the emulsion applied to the outer surface may require a lower oil concentration than the emulsion of the sock liquid, or it may be necessary to take measures such as applying it only to a necessary portion.

In order to disperse the silicone emulsion on both sides of the film and to impart slipperiness to both sides, it is necessary to use a method of transferring the silicone emulsion on the film-coated surface to the non-coated surface after stretching. The transfer method is to peel off the tubular double film folded after stretching into a single film (single sheet) and wind this single film into a roll to bring the emulsion coated surface into contact with the non-coated surface. It is preferable to carry out. In practice, the film is rolled into a roll shape by using a normal slitting process that separates the formed film into single pieces and divides the film into a width suitable for actual packaging. It is simpler and more preferable because it does not require a step.

Since the silicone emulsion is provided on both sides of the film, the following effects can be obtained by the transfer method. That is, immediately after stretching, the amount of the antifogging agent that bleeds and exists on the film surface on the coated surface of the film is not so large, and a very small amount forms a layer on the film surface, and the sock liquid is further formed on it. The silicone emulsion applied as is forming a layer. The film is stretched in this state, and then the film is rolled into a roll using a single slit process, and when the non-coated surface is brought into contact with the emulsion layer on the coated surface, only the silicone emulsion is easily transferred evenly. The surface abundance of the silicone emulsion tends to be uniform on both the surface and the non-coated surface. In addition, this method is particularly effective when it is desired to make the coating layer as thin as possible or to coat a very small amount because the coating amount of the silicone emulsion per area on the final film is reduced by stretching after coating. .

The stretching conditions for stretching after coating are preferably conditions (stretching temperature) at which the morphology of the oil particles in the emulsion is not destroyed as much as possible, preferably 80 ° C. or lower, more preferably 60 ° C. or lower. It is better to stretch. In this case, it is easy to maintain the state where the silicone oil is dispersed in the aqueous phase in the form of particles in the applied silicone emulsion immediately after stretching. Then, after transfer by the slit, the antifogging agent bleeds between the oil particles on the film to cover the particles, and thus more effective antifog property is expected to be exhibited. Regarding the slipperiness, there is no problem even if the oil surface is covered with the antifogging agent as long as the coating amount of the silicone oil is within the range of the present invention.

Also, when the direct inflation method of directly blowing up from the die is used, the same coating method as the above method may be used. In that case, if the sock liquid is used, it is preferable to use between the nip rolls before the slit process of the ears in the tubular film before slitting the ears. Also in the case of the T-die method, it is preferable to apply the silicone oil in any step from immediately after extrusion to stretching, as in the circular die method.

Further, a flat film formed by the T-die method or a film formed by the inflation method and cut open into a single film is coated with silicone oil on one surface off-line, and then, for example, wound in a roll shape on the non-coated surface. It may be transferred. However, among the above-mentioned methods, it is preferable to apply silicone oil to the tubular raw material before stretching and then to stretch, since a small amount can be coated.

Further, especially when antifogging property and slipperiness are not required on the entire surface of the film, for example, a silicone oil or a silicone emulsion is directly applied to only a portion of the film where the slipperiness is to be imparted, using a coater or the like. Any method may be used, and transfer is not particularly required. The formed film may be heat-treated before or after the stretching step in order to improve dimensional stability. To improve the surface properties of the film, such as corona treatment, to improve the wettability of the film with anti-fog agents or silicone oil, or to improve the heat resistance of the film Electron beam irradiation or the like may be performed as necessary.

The thickness of the obtained film is preferably 2 to 50 μm, and more preferably 5 to 25 μm when used for packaging. The film formed as described above needs to have a total of 200% elongation loads in the longitudinal and transverse directions of 1500 g / cm width or less in order to impart stretchability suitable for stretch packaging, and more preferably. Is preferably in the range of 200 to 1200 g / cm width. The total value of 200% elongation load in length and width is 150
If the width exceeds 0 g / cm, the film becomes difficult to stretch and the stretchability deteriorates. When it is tray-wrapped with a packaging machine, wrinkles are likely to remain on the surface of the film without a heat tunnel, and the appearance tends to be very poor. .

The longitudinal / lateral ratio of a 200% elongation load is
Preferably within the range of 1-10, more preferably 1-5.
In many cases, the packaging finish will be better if it is within the range. In order to adjust the 200% elongation load within the above range, for example, when a mixed resin is used, softer ones are added, stretching conditions such as stretching temperature and stretching ratio are adjusted, or heat treatment before and after film formation is performed. A known method such as adjustment of heat treatment conditions such as temperature and heat treatment time may be used.

[0043]

As described above, the film of the present invention is
(A) applying a silicone emulsion to one side of a raw film preliminarily containing an antifogging agent, and then stretching; and (b) applying a silicone emulsion coating surface of the stretched film to a stretched film not coated with the silicone emulsion. It is possible to make the amount of silicone oil applied to the film surface extremely small, such as 0.3 to 50 mg / m ² , by contacting the other surface with a method such as winding it in a roll and transferring it. It is possible to obtain the effect that even and uniform coating can be performed.

Therefore, in the film of the present invention, since the silicone oil imparts appropriate slipperiness to the film,
The problems such as scratches when the film is conveyed from the inside of the wrapping machine are significantly improved compared to the conventional polyolefin stretch film, and the mechanical easiness is greatly improved. Further, in the present invention, the antifogging property is also good and it lasts for a long time. Although the mechanism of development of antifogging property is not clear exactly, especially when the O / W type emulsion adheres to the film, the oil particles are dispersed and exist on the surface of the film immediately after the film formation. An antifogging film is formed on the nonexistent portion. The oil itself does not have anti-fogging properties, but the oil exists in the form of very fine particles (usually a diameter of 0.01 μm to 1.0 μm), which is the size of water droplets that can cause problems with anti-fogging properties. Since it is much smaller than (usually diameter 0.1 mm to 30 mm), the oil part does not interfere with the anti-fogging property of the film as a whole, or the film of the above anti-fogging agent wraps the oil particles and is the maximum of the film. It is considered that an antifogging agent layer is formed on the outer surface. Also, in the latter idea, even if the oil particles on the film do not maintain the particle state and the film collapses to a film-like shape after a lapse of time after film formation, the antifogging agent film already has a considerable portion of the oil particles. It is considered that the antifogging property is not hindered because it is formed in the form of wrapping.

[0045]

EXAMPLES Examples of the present invention will be specifically described below, but these do not limit the present invention in any way. In addition, the measuring method of the evaluation item in an Example is demonstrated below. (1) [Collar length] When creating a measuring device that imitates the transport mechanism of a general stretch wrapping machine and transporting the film, the misalignment length caused by the film curling like a strand from the regular stop position at the front end of the film Measured as length. The regular stop position is the position where the leading edge of the film should be stopped after the film has been conveyed for a certain distance, assuming that the film is in complete contact with the film feed rubber belt, and is unique to the machine. is there.

During transport, the film is held in close contact with a rubber belt for transporting the film, and this belt is moved by a motor for transport. At this time, the film is transported while rubbing the film feed plate fixed to the apparatus. The film pressing plate is a plate made of high-density polyethylene, and the film feed belt has a width of 20 mm and is 10 mm in length in the surface holding the film.
It is a polyurethane rubber having protrusions having a length of 2 mm, a width of 20 mm, and a height of 0.5 mm for each mm.

For the measurement, the film is sandwiched between the film pressing plate and the rubber belt, and a load is applied by a spring so that the protrusion of the rubber is 1.0 Kg / cm ^2, and the belt and the film are brought into close contact with each other at a constant distance ( 400 mm), the belt length is measured when the belt is suddenly started and stopped at a relative speed of 60 cm / min. Specifically, a commercially available packaging machine (Teraoka Seiko Co., Ltd. AW2600jr (PVC specification)) or the like is preferable as a model machine. Further, a measuring device made by modeling the film conveying portion (friction portion) of these packaging machines may be used. A length of 20 mm or less was accepted.

(2) [Anti-fog property] A plastic container containing 200 cc of tap water at 20 ° C. was wrapped with a film to be measured, the container was stored in a refrigerator at 5 ° C. for 30 minutes, and the state of the film was observed. Judgment was made according to the following criteria, and an antifogging property of 4 points or more was passed. Anti-fogging property 1 point: A fog-like fog is generated on the entire surface of the film and the inside of the film cannot be seen. Anti-fogging property 2 points: Transparent water droplets of 2 to 5 mm are formed on almost the entire surface. The inside can be seen temporarily. Anti-fogging property 3 points: Water droplets of 10 to 20 mm occupy almost the entire surface. Anti-fogging property 4 points: Intermediate of 3 to 4 points. Partially continuous water film can be seen, but the inside can be seen well. Anti-fog property 5 points: A continuous mirror-like water film is seen on the entire surface and the inside can be seen well. (3) [Cellotape adhesiveness (g / 20mm width )] A cellophane tape is attached to the film to prepare a strip-shaped sample having a width of 20 mm, and the peel strength between the cellophane tape and the film of this strip-shaped sample is measured by a tensile tester.

(4) [Heat Sealing Property] The tray-packaged sample was bottom-sealed with a commercially available heat sealer, and evaluated in the temperature range where the sealed condition was good.
The higher the upper limit and the lower the lower limit of the temperature range, the better. (5) [200% elongation load (g / cm width)] Strips sampled with a film width of 10 mm and a length of 100 mm were set in a tensile tester so that the chuck length was 50 mm, and pulled at a pulling speed of 200 mm / min. Then, the load value when the elongation reaches 200% is read and used as the measured value. However, when the film breaks at less than 200%, a tangent line is drawn at the time of elongation 20% before the time at which it breaks in the graph of elongation vs. elongation load, and this is 200
The measured value is obtained by extending the value to the point of% elongation. In this way, the total value measured in the longitudinal and transverse directions of the film is taken as the 200% elongation load. in this case,
The vertical direction is the film flow direction during film formation, and the horizontal direction is the direction perpendicular to the vertical direction.

(6) [Actual packaging test] As a stretch packaging machine, a packaging machine A for PVC of Teraoka Seiko Co., Ltd.
W2600 jr (PVC) was used for tray packaging, and the appearance of the saw during transport and the packaging finish were evaluated as follows, and only the film with the A rating was accepted. A: The twist is 20 mm or less and there is no film wrinkle on the tray surface after packaging. B: The twist is 20 mm or less, but the film has wrinkles on the tray surface after packaging. C: The twist is 20 mm or more, but the film has wrinkles on the tray surface after packaging. None D: Twist is 20 mm or more and film wrinkles appear on the surface of the tray after packaging. (7) [Optical properties] A haze value was determined according to JIS K6714.

(8) [Amount of antifogging agent surface] The surface of the film was carefully rubbed with KBr powder to adhere the entire amount of the surface antifogging agent to KBr powder, and the powder was quantitatively recovered and then pressurized. It was made into a sheet. This sheet was measured by an infrared spectrometer, and the surface amount was judged from the size of the peak of the wavelength peculiar to the antifogging agent added on the chart.

(9) [Silicone oil coating amount] After the amount of Si element on the film is quantified by the fluorescent X-ray method, the amount of oil is calculated by converting it to the weight of dimethylpolysiloxane molecules forming silicone oil. (By molecular weight conversion)

[0053]

Example 1 The layer A (surface layer) was an ethylene-vinyl acetate copolymer (hereinafter, EVA, vinyl acetate content 15% by weight, melt index (MI) = 2.0): 100% by weight, and the layer B ( The middle layer) is EVA: 61% by weight, ethylene-propylene copolymer thermoplastic elastomer (hereinafter, E)
PP, propylene content 15 mol%, MI = 0.4
5): 22% by weight, crystalline polypropylene (hereinafter, P
P, MI = 7): 17 wt% mixed composition, and C layer (middle core layer) is PP: 100 wt%, A layer, B
A layer and a C layer are laminated in the order of A / B / C / B / A, and a 5-layer film having a thickness ratio of each layer of 15/30/10/30/15 is coextruded by using an extruder and a circular die. The unstretched film stock on the formed cylinder is once folded and rapidly cooled in a water bath, then reheated to 50 ° C and stretched 3 times vertically and 3 times by the inflation method to fold this tubular film. After that, a single slit was performed to obtain a film having a thickness of 15 μm.

Diglycerin monolaurate was used as an antifogging agent by in-line injection into layers A and B with an extruder, and the surface amount of the antifogging agent was adjusted by the injection amount. For coating the silicone oil, dimethylpolysiloxane (viscosity 400 centistokes) was used as the silicone oil, and an O / W type emulsion (oil particle size 0.4 μm) using an anionic surfactant as the emulsifier was used. The amount of coating on the film was adjusted by diluting the emulsion with ion-exchanged water and adjusting the oil concentration.

The silicone emulsion is applied by using a sock solution, and when the extruded cylindrical unstretched film original is folded in a water bath, it is injected as a sock solution into the inner surface of the tube.
Adjusting the nip roll pressure to control the coating amount uniformly to apply a predetermined amount to the inner surface of the original fabric, and then wind the slit single film into a roll by using the single slit process after stretching. The silicone emulsion was also transferred to the outer surface, which is the non-coated surface.

Table 1 shows the physical properties and packaging characteristics of the stretch film thus formed. As shown in Table 1, this film has a 200% elongation load, an antifogging agent surface amount,
The amount of silicone oil applied is within the scope of the present invention,
The antifogging property, the twisting property, and the evaluation by actual packaging were also good.

[0057]

Comparative Example 1 Layer B of the film has EVA: 48% by weight, E
A film was formed in the same manner as in Example 1 except that PP: 13% by weight and PP: 39% by weight. 200% due to the large amount of relatively hard resin used as film raw material
This is an example when the extension load becomes too large.

[0058]

Examples 2 to 4 and Comparative Examples 2 to 4 Films having the physical properties shown in Table 1 were formed in the same manner as in Example 1 except that the surface amount of the antifogging agent and the coating amount of silicone oil were changed. Got
However, Comparative Example 2 is an example in which the surface amount of the antifogging agent is too small, and Comparative Examples 3 and 4 are examples in which the silicone oil coating amount is too small and excessive.

[0059]

Example 5 Layer B of the film was EVA: 61% by weight, E
A film was formed in the same manner as in Example 1 except that PP: 17% by weight and PP: 22% by weight.

[0060]

[Example 6] A film was formed in the same manner as in Example 1 except that the silicone-based lubricant was applied by a coater only after the film formation single slit, instead of using a sock liquid. Got Above, Example 1
6 and Comparative Examples 1 to 4 had good film-forming properties without any problems.

[0061]

Reference Example 1 A vinyl chloride film which is generally commercially available is given as an example.

[0062]

[Table 1]

Table 1 shows the physical properties and packaging characteristics of the film formed as described above. All of Examples 1 to 6 were good in both mechanical susceptibility and antifogging property. In particular, in the packaging test in the actual stretch packaging machine using the film after the single slit, whether the surface contacting the tray is the silicone oil application surface or the transfer surface, the film on the tray surface There was no problem of wrinkles, there was no problem of conveyance failure due to "stretching" caused by friction with the film pressing plate, and scratches due to rubbing of the film were significantly improved. These improving effects were satisfactorily maintained immediately after the single slit and even after the film was stored at room temperature for 30 days.

In addition, the above-mentioned AW of Teraoka Seiko Co., Ltd.
Stretch wrapping machines other than 2600 jr (PVC) (Fujipack AUTOMAC A18X, and Ishida Co., Ltd.)
Wmini MarkII U) was also subjected to a packaging test, and all were successfully packaged. Stretch wrapping machine with polyolefin film specifications (Teraoka Seiko AW2)
Even at 600 jr (PE), there was no problem in packaging suitability.

Not only that, but there was no deterioration in optical properties, heat sealability and adhesiveness to cellophane tape which was a concern due to the application of silicone oil, and the balance of the properties required as a stretch film was very good overall. On the other hand, in Comparative Example 1, the 200% elongation load of the film was too large as a stretch film, and therefore wrinkles of the film on the tray surface could not be removed even after packaging, and the packaging finish was poor. Further, in Comparative Examples 2 to 4, since the surface amount of the antifogging agent or the amount of silicone oil applied was unsuitable, it was not possible to exert both the antifogging effect and the antifogging property at the same time.

[0066]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, not only the stretch wrapping machine of the polyolefin film type has excellent wrapping property, but also the stretch wrapping machine of the PVC film type does not suffer from twisting or scratches. (EN) Provided is a polyolefin-based stretch film film which has a significantly improved problem in transportation, can be favorably packaged, and has excellent antifogging property and other surface properties, and which is highly useful.

Claims (2)

[Claims] 1. A film having a total of 200% elongation loads in the longitudinal and transverse directions of 1500 g / cm width or less, at least one surface of the film being a layer made of a polyolefin resin, and at least a part of the film. A film for stretch packaging, characterized in that 0.3 to 50 mg / m ² of silicone oil and 0.5 to 50 mg / m ^{2 of} an antifogging agent are arranged on one surface thereof. 2. A silicone emulsion is applied to one side of a raw material film containing an antifogging agent, which is formed by heating and melting a resin raw material with an extruder, and then the raw material film is stretched in at least one axial direction. After that, the silicone emulsion-coated surface of the stretched film is further brought into contact with the non-coated surface to transfer the silicone emulsion to the non-coated surface, and the silicone emulsion is placed on both surfaces of the film. Manufacturing method.