JPS6025455B2 - Film resin composition for adhesive packaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film resin composition for adhesive packaging that utilizes the adhesiveness of the film for packaging, and in particular to packaging called stretch packaging, in which an object is wrapped by stretching the film. The present invention relates to an ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) resin composition suitable for use as a film for commercial use.

Stretch wrapping is done using automatic wrapping machines or hand wrappers (
Items of various shapes can be tightly packaged using a manual packaging machine (manual packaging machine), the packaging condition can be fixed by lightly pressing or heat sealing the films, and the appearance of the packaged items can be beautifully packaged. It is especially used for packaging fresh foods because it significantly increases the commercial value of products and prevents the freshness of the packaged items such as food from decreasing.

The main physical properties that the film used for stretch packaging should have are as follows.

(a) It must have excellent adhesion (b) It must have excellent lubricity (c) It must have an appropriate elongation (d) It must have excellent mechanical strength (e) It must have excellent optical properties such as transparency It has good cloud-proofing properties Currently, the most commonly used films are soft pinyl chloride resin films containing a large amount of plasticizer, but on the other hand, EVA
Films based on these have also been developed.

For example, in Tokusekki No. 49-60352, EVA
A film is disclosed in which 5 to 3 parts by weight of a tackifier such as an aliphatic hydrocarbon resin, rosin, or polyterbene resin is added to the film. However, this film containing only a tackifier has a significantly large scale friction coefficient on the film surface.
This film has problems such as poor tenacity, poor slippage with the packaged item or tray during packaging, and a tendency for the film rolled into a roll to block easily. The present inventors have taken into consideration the above-mentioned problems of conventional EVA-based films, and have created a film with high adhesiveness by imparting toughness to the film surface and preventing blocking of the film. As a result of intensive research into EVA resin compositions, the present invention was discovered, and it was discovered that the film obtained from the EVA resin composition of the present invention is particularly suitable as a stretch packaging film. It is something that

That is, the present invention has a melt index of 0.5 to 15.
In the evening, 10 minutes, an adhesive consisting of 97.99-84.8% by weight of an ethylene-pinyl acetate copolymer having a vinyl acetate group content of 5-3% by weight, and at least one type of rosin ester. 5-5% by weight, at least one {B} mineral oil 1-5% by weight, at least one ■0.5-5% by weight of nonionic surfactants, and at least one ■ Polyalkylene cable polyols 0.01-0
．． 2% by weight of an adhesive packaging film resin composition.

The EVA used in the present invention has a melt index of 0.5 to 15 minutes/10 minutes and a vinyl acetate group content of 5 to 3.
% by weight of EVA.

The melt index is a value measured according to JIS K-6760, and the film made of the resin composition of the present invention using EVA of less than 0.5 mm and 10 minutes has decreased transparency and gloss; If the time exceeds 10 minutes, a so-called drawdown phenomenon will occur, in which the film will flow and become difficult to form during film processing, making film processing difficult and increasing the blocking phenomenon of the film. In addition, the vinyl acetate group content is a value determined by elemental analysis, and if less than 5% by weight of EVA is used, the adhesiveness, transparency, and gloss will decrease, and if it exceeds 3% by weight, the film will Drawdown is likely to occur during processing, and blocking of the film becomes significant.

In the EVA used in the present invention, the preferred range is:
Melt-in desk 0.5-10 evenings/10 minutes, vinyl acetate group content 5-2% by weight, more preferred ranges are:
The melt index is 0.5-10 minutes, and the pinyl acetate group content is 5-15% by weight. In addition, to the EVA mentioned above,
If necessary, resins such as polyethylene, crystalline ethylene-propylene random copolymer, and crystalline 1,2-polybutadiene may be added. The adhesive comprising at least one type of wind rosin ester used in the present invention is:
Gum rosin, wood.

Gin, tall oil rosin, hydrogenated. gin, polymerized rosin, etc. It is a mixture of one or more types of esters of resin and esters such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin, bentaerystol, etc., and is 0.5 to 5% by weight, preferably 1 to 3% by weight. It is added. These rosin esters are
It was selected because it develops tackiness with a small amount of addition, does not impede the transparency and gloss of the film, has excellent solubility in mineral oils (described below), and has excellent heat resistance stability. FDA (Food and Food)
Preferred are the rosin esters described in subpart F121.2592 (abbreviation for DrugAdministrauon), especially esters with glycerin and pentaerythritol. If the amount added is less than 0.5% by weight, preferred adhesive strength cannot be obtained, and if it exceeds 5% by weight, blocking phenomenon of the film may occur, which is undesirable. At least one used in the present invention
Species [B' Mineral oils are liquid hydrocarbons consisting of one or a mixture of two or more selected from paraffinic, isoparaffinic, and naphthenic oils, and have a boiling point of at least 200oo or more under atmospheric pressure. is preferably added in an amount of 1 to 5% by weight, preferably 1 to 3% by weight.

Specifically, mineral oils as described in FDA Subpart F121.2 Part 9, white mineral oils as described in FDA Subpart D121.1146, FDA Subpart D121.11
Preferred are the odorless light hydrocarbons described in No. 82.

When these mineral oils dissolve and plasticize the adhesive, they both plasticize and soften the EVA and increase the adhesiveness of the film. Moreover, the mineral oils pre-prepared on the film surface act as a lubricating layer, imparting lubricity to the film surface. Furthermore, the mineral oils contained inside the film prevent light scattering at the dispersion interface between EVA and the adhesive, and the mineral oils that bleed onto the film surface eliminate fine irregularities on the film surface. This is probably because the film has a smooth surface and reduces light scattering on the film surface.
This further improves the transparency and gloss of the film. As mentioned above, mineral oils can be used in combination with adhesives made of rosin esters to improve adhesiveness and
A film with excellent properties, transparency, and gloss can be obtained.

If the amount added is less than 1% by weight, the above-mentioned effects of the mineral oils will not be sufficient, while if it exceeds 5% by weight, the film will be excessively plasticized and softened, and excessive bleeding will occur on the film surface. As a result, the surface of the film becomes sticky, and packaging workability is significantly reduced.
The at least one type of {C} nonionic surfactant used in the present invention includes polyhydric alcohol fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyhydric alcohol fatty acid ester, and polyoxyethylene fatty acid ester. One or a mixture of two or more selected from tyrene fatty acid ester, polyoxyethylene alkyl ether, etc., 0.5 to 5% by weight, preferably 1 to 2% by weight
It is added.

Examples of polyhydric alcohol fatty acid esters include glycerin,
Polyhydric alcohols such as polyglycerin, sorbitan, bentaerythritol, and alkyl groups with 5 to 13 carbon atoms
Straight chain saturated fatty acid or alkyl group with 17 to 2 carbon atoms
Preferred are esters with direct mirror saturated fatty acids of No. 1 and the like.

Preferred examples of the polyoxyethylene alkyl phenyl ether include polyoxyethylene alkyl phenyl ether and polyoxyethylene alkyl phenyl ether having 4 to 12 ethylene oxide units. The polyoxyethylene polyhydric alcohol fatty acid ester is preferably one obtained by adding 5 to 2 units of ethylene oxide to the above-mentioned polyhydric alcohol fatty acid ester. As the polyoxyethylene fatty acid ester, an ester of polyoxyethylene having 3 to 1 ethylene oxide units and the above-mentioned fatty acid is preferable. As the polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene oleyl cetyl ether, polyoxyethylene tridecyl ether, etc. each having 5 to 1 ethylene oxide are preferable. These nonionic surfactants are preferably liquid in normal state from the viewpoint of solubility with other additives, and in particular, the above-mentioned polyhydric alcohol fatty acid esters and polyoxyethylene alkylphenylables. ，
and mixtures thereof are preferred.

If the amount added is less than 0.5% by weight, the necessary anti-fogging properties will not be imparted, and if it exceeds 5% by weight, the added nonionic surfactants will excessively bleed onto the film surface, resulting in poor film quality. This is undesirable because it causes the surface to become contaminated or sticky. The at least one rib polyalkylene ether polyol used in the present invention is one or a mixture of two or more selected from polyethylene glycol, polypropylene glycol, polybutylene glycol, etc. .2% by weight, preferably 0.01 to 0.15% by weight.

These polyalkylene ether polyols have a boiling point of at least 200 oo or more under atmospheric pressure,
A liquid in normal state having a viscosity of 23 qo (measured with a Brookfield rotational viscometer) of 100 ps or less is preferred from the viewpoint of solubility with the other additives mentioned above.

Especially the average molecular weight 200-600 and further 300-400
polyethylene glycol, average molecular weight 400-300
0 and more preferably 1000 to 2000 polypropylene glycol. If the amount added is less than 0.01% by weight, the tenacity of the film will not be improved and the blocking phenomenon will likely occur, which is undesirable. If the weight percentage exceeds
Although the lubricity and anti-blocking properties of the film are improved, on the other hand, the tackiness is considerably reduced, or the film surface becomes contaminated with white spots. As stated above, the adhesive packaging film resin composition of the present invention is made of EVA
The above-mentioned four types of additives are added to the film, and the film has the optimum properties as an adhesive packaging film, especially as a stretch packaging film. It is possible to obtain a film that eliminates the blocking properties of the film, and the so-called contradictory properties of the film, such as tackiness, density, and anti-blocking properties, can be kept within an appropriate range through the combination and synergistic effect of the four types of additives mentioned above. It is a novel resin composition that can yield a film that is excellent in transparency and gloss, and also has cloud-proofing properties.

The types, amounts added, and combinations of the above four additives are appropriately selected depending on the required film characteristics, the type of EVA, etc.; In order to improve properties, it is preferable to add a slightly larger amount of polyalkylene ether polyols. These four additive mixtures are
2.01 to 15 for A. a% by weight, preferably 3.
It is added in an amount of 01 to 8.15% by weight. The resin composition of the present invention can be prepared by preparing a masterbatch using a commonly used method using one of the four additives described above or a mixture of two or more additives, and blending the mixture to a predetermined amount. can get. The four types of additive mixture consisting of the preferable types and amounts of additives of the present invention can be flooded to about 100 oo, so that the rosin esters are dissolved in the mineral oils to form a homogeneous solution, and the dissolved additives are mixed together. Even if the liquid is cooled to room temperature, it remains in a solution or jelly-like state, so it can be flooded as necessary and a predetermined amount of the additive mixture can be poured into the extruder cylinder using a metering pump from the additive inlet installed in the cylinder. It is also possible to obtain a resin composition and form a film at the same time. A film can be obtained from the resin composition of the present invention by a commonly used method, for example, by using an extruder equipped with an annular die or a T-die. In order to improve the properties, it is preferable to carry out stretching using a known method.

As described in the examples below, the film obtained from the resin composition of the present invention has a coefficient of friction of 0.5 or less, an adhesive force of 5 ta or more, and a roll peeling force indicating blocking property of 6 ta.
As an adhesive packaging film, especially as a stretch packaging film, it has good adhesion, tenacity, and anti-blocking properties, and has a haze value of less than 3%, which indicates transparency, and gloss. If the film has an excellent gloss value of 100 or more, it is a film with anti-cloud properties.

The coefficient of dynamic friction is a value measured in accordance with ASTM D-1894-63T, and if the coefficient of dynamic friction is 0.5 or more, the frictional resistance with the packaged object, tray, etc. during packaging becomes large.
This not only impedes packaging work efficiency, but also causes the film to get stuck to protruding parts of the packaged items, the edges of the tray, etc., or to break.

To test the adhesive strength, cover the film on the middle 125 side, length 25Q snout, and 2 feet thick rubber sheet to avoid wrinkles.
The periphery was secured with cellophane tape, and a 125-piece identical sample film was placed on top of it to avoid wrinkles, and a rubber roll with a diameter of 2 mm, length of 30 mm, and weight of 300 mm was used to press and adhere the film. Pull in the length direction at a speed of 125 per minute so that the angle between them is always kept at 120 degrees,
This value is a measurement of the force required to peel off the film, and is necessary to secure the packaging state with the adhesive force between the films after packaging.The larger the value, the better, but from the viewpoint of packaging workability, 5 ta or more is recommended. preferable.

The roll peeling force is determined by winding the film into a roll for 200 min and storing it at a winding tension of 50 min/kite (per film center).
It is the value obtained by dividing the force required to pull out the film from the roll at a speed of 60 m/min by the film's core strength, which indicates the blocking property of the film, and is preferably 7 m/min or less, more preferably 6 m/min or less.

If this value is large, the film will block when stored for a long time or in a relatively high temperature place, making it difficult to pull out the film from the roll. Haze is a value measured according to ASTM D-1003-61, and is preferably 5% or less, and preferably 3% or less.

If it exceeds 5%, the transparency of the film is poor, making it difficult to see through the packaged items, which is undesirable in terms of the commercial value of the packaged items.

Gloss is a value measured in accordance with ASTM D-2457-65T, which indicates the gloss of the film surface, and is preferably 100 or more. Cloud resistance is the commercial value of the packaged item, which occurs when the packaged item contains water or is stored at low temperatures, and water droplets adhere to the film surface, clouding the film surface and making it impossible to see through the packaged item. This is necessary to prevent a decline in

A film was placed over a 200' volume beaker containing 100 liters of water at a temperature of 2-0, and left in a heated bath set at 5°C for 10 minutes. Judging with the naked eye, △ or above, even ○
The condition is preferable. ○: No water droplets attached.

Δ: Water droplets are partially attached.

×: Water droplets adhere to the entire surface of the film, and the transparency of the film is reduced.

Next, the present invention will be described in more detail based on representative examples.

Example 1 Melty Sodex 1.5, EVA with a vinyl acetate group content of 10% by weight, and EVA with a vinyl acetate group content of 10% were melted through a 5-diameter annular die with a 0.5-rib slit provided at the tip of a 45-rib extruder. ,
A resin composition consisting of additives (using a masterbatch) shown in Table 5 selected from the additives shown in Tables 1 to 4 was heated in an extruder at a maximum temperature of 190q0 in the cylinder part, a temperature of 180do in the die part. Extrude downward at a rotational speed of 88 pm, expand so that the ratio of the diameter of the die to the diameter of the tubular membrane is 1.3, and create a slit for water to come out inside at a position of 20 arcs from the tip of the die. Using a water ring, lyo water was brought into contact with the tubular membrane at a rate of 4 solitres/min so as to surround it, and the membrane was cooled and solidified.

This tubular membrane was taken off with nip rolls at a take-up speed of 5 m/min so that it had 10 folds and a thickness of 270 mm to obtain a raw fabric. The obtained raw fabric is passed through a heating tube equipped with an annular infrared heating heater, heated to about 140°C, and inflated by introducing air to 5 times the diameter of the raw fabric, and then heated with an air ring. cooled and withdrawn at a withdrawal speed of 15/min;
Slits were removed from the ends of the film to obtain a medium-3 ratio film, which was peeled into two pieces and wound into a roll having a length of 200 mm.

The thickness of the film is 18r. 23 of the resulting rolls
Annealing was performed for 10 days in a constant temperature room at 0.00 and 50% humidity, and the physical properties of the film were measured using the method described above and are shown in Table 6.

The obtained film has a dynamic friction coefficient of 0.5 or less and an adhesive strength of 5.
．． It was an excellent film with well-balanced lubricity, adhesiveness, and anti-blocking properties, with a roll peeling force of 5 mm/skin or less and a roll peeling force of 5 mm/skin or less.

Manual wrapping machine [Hand wrapper manufactured by Nihon Sangyo Kikai ■ One day W-4
6-B type] was used to perform stretch wrapping using a tray containing 200 yen clay plates. As a result, packages with good tension and no wrinkles were obtained for each film. In addition, the film folded into the bottom of the tray is fixed by the adhesive force of the film, and before the film is welded and fixed by heat sealing, the stretched film loosens due to the elastic recovery force of the film, causing many wrinkles. The film had excellent adhesiveness and did not have a weak packaging condition. Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Example 2 Similarly to Example 1, EVA with a melt index of 0.6 and a pinyl acetate group content of 15% by weight, A film with a thickness of 18 mm was obtained from a resin composition containing each additive shown in the table.

Note that the heating temperature of the original fabric was 13,000. The physical properties of the obtained film are shown in Table 8, and it was a film that yielded similarly to Example 1, and also had good packaging properties.

Table 7 Table 8 Comparative Examples In the same manner as in Examples 1 and 2, a film having a thickness of 18 peaks and having the additive composition shown in Table 9 was obtained.

In addition, the gunwale. 1 and M. 2 is EVA used in Example 1,
No. 3 and the gunwale. In Example 4, the EVA used in Example 2 was used. The physical properties of the obtained film are shown in Section 1. NO
．． 1 and no. The film of No. 2 was the same as that of Example 1. 3
, No. 4, No. This is a comparative example with the film of No. 5. 1 has an additive composition excluding polyethylene glycol. No. 2 contains 0.25% by weight of polyethylene glycol, which is more than the range of the present invention. No. For film No. 1, when measuring the coefficient of dynamic friction, the measuring warp (metal plate) got stuck on the film, and the film was torn, making it impossible to measure.
It was a film with no inertia. Furthermore, the roll peeling force is 8
It was difficult to remove the film from the roll, and when the film was pulled out forcibly, the film stretched locally or broke. M. The film No. 2 had good friction coefficient and roll peeling force, but on the other hand, the adhesive strength was 3.5 mm and 4.5 mm, so when it was packaged in the same manner as in Example 1, the bottom part after stretching was Before the folded film is heat-sealed, the adhesive force of the film does not hold it in place, and the stretched film loosens due to the elastic recovery force of the film, resulting in a wrinkled and weakly wrapped package, causing the packaged product to deteriorate. value,
It was a film that reduced packaging workability and was difficult to put into practical use. In addition, white spot-like contamination occurred on the film surface. shame. 3 and shame. Film No. 4 is a comparative example with Example 2, and film No. 4 is a comparative example with Example 2. 3 is an additive composition excluding polyethylene glycol, and a ship. No. 4 is a vessel to which polyethylene glycol is added in an amount greater than the scope of the present invention.
3 and the above axis. Shows the same forehead as 1, and is also embarrassed. 4 is the above M. Both films showed the same tendency as No. 2 and were difficult to use for visual purposes. Table 9 Table 10

Claims (1)

[Scope of Claims] 1. 97.99 to 84.8% by weight of an ethylene-vinyl acetate copolymer having a melt index of 0.5 to 15 g/10 min and a vinyl acetate group content of 5 to 30% by weight, and at least 0.5 to 5% by weight of an adhesive consisting of one type of (A) rosin ester and at least one type of (B) mineral oil 1 to 5% by weight
% by weight, at least one (C) nonionic surfactant 0.5-5% by weight, and at least one (D) polyalkylene ether polyol 0.01-0.2% by weight. A film resin composition for adhesive packaging, characterized in that it consists of. 2 The ethylene-vinyl acetate copolymer has a melt index of 0.5 to 10 g/10 minutes and a vinyl acetate group content of 5 to 2.
The film resin composition for adhesive packaging according to claim 1, which has a content of 0% by weight. 3 Ethylene-vinyl acetate copolymer has a melt index of 0.5 to 5 g/10 minutes and a vinyl acetate group content of 5 to 15
% by weight of the adhesive packaging film resin composition according to claim 1. 4 Rosin esters include gum rosin, uddrosin,
Tall oil rosin, hydrogenated rosin, polymerized rosin, diethylene glycol, triethylene glycol, glycerin,
The adhesive packaging film resin composition according to claim 1, which is an ester with bentaerythritol. 5 Rosin esters include gum rosin, uddrosin,
The adhesive packaging film resin composition according to claim 1, which is an ester of hydrogenated rosin, glycerin, and bentaerythritol. 6. The film resin composition for adhesive packaging according to claims 1, 4, and 5, wherein the amount of rosin ester added is 1 to 3% by weight. 7. The film resin composition for adhesive packaging according to claim 1, wherein the amount of mineral oil added is 1 to 3% by weight. 8. The film resin composition for adhesive packaging according to claim 1, wherein the nonionic surfactant is a polyhydric alcohol, a fatty acid ester, a polyoxyethylene alkyl phenyl ether, or a polyoxyethylene polyhydric alcohol fatty acid ester. thing. 9 The polyhydric alcohol fatty acid ester is an ester of glycerin, polyglycene, sorbitan, bentaerythritol and an alkyl group and a straight chain saturated fatty acid having 5 to 13 carbon atoms or an alkyl group and a straight chain unsaturated fatty acid having 17 to 21 carbon atoms. A film resin composition for adhesive packaging according to certain claims 1 and 8. 10. Claims 1 and 8, wherein the polyoxyethylene alkyl phenyl ether is polyoxyethylene (n=4-12) nonyl ether, polyoxyethylene (n=4-10) octyl phenyl ether A film resin composition for adhesive packaging as described in 1. 11 Addition amount of nonionic surfactants is 1 to 2% by weight
Claims 1, 8, 3, 9, and 10
A film resin composition for adhesive packaging as described in 1. 12. The film resin composition for adhesive packaging according to claim 1, wherein the polyalkylene ether polyol has a boiling point of at least 200°C or higher at atmospheric pressure and a viscosity of 1000 cps or lower at 23°C. 13. The adhesive packaging film resin composition according to claim 1, wherein the polyalkylene ether polyol is polyethylene glycol having an average molecular weight of 200 to 600 or polypropylene glycol having an average molecular weight of 400 to 3,000. 14. The film resin composition for adhesive packaging according to claims 1, 12, and 13, wherein the amount of polyalkylene ether polyol added is 0.01 to 0.15% by weight.