JP2001323114A - Stretched film for hand wrapping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretched film which has an elongation suitable for hand wrapping, is hardly broken when stretched, and has a sufficient stickiness. SOLUTION: This film comprises a linear low-density polyethylene (A) having a density higher than 910 kg/m3, a linear low-density polyethylene (B) having a density of 910 kg/m3 or lower, a high-pressure polyethylene (C), and a component (D) such as a petroleum resin, terpene, or rosin. Based on the sum of ingredients A, B, and C, the amounts of ingredients A, B, and C are 90-20 wt.%, 5-40 wt.%, and 5-40 wt.%, respectively, and the amount of ingredient D added is 0-10 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stretch film for hand wrap used for food packaging.

[0002]

2. Description of the Related Art Stretch films for food packaging are used by directly overlapping foods such as fruits and vegetables, fresh fish, meat, and side dishes on a lightweight plastic tray such as polystyrene paper (PSP), and stretching the films to overlap. Is done. As the type of film, a film for auto wrap (hereinafter referred to as “auto”) suitable for packaging by an automatic wrapping machine and a hand wrap suitable for packaging by a packaging worker using a handler wrapper ( Hereinafter referred to as "hand".) There is a film.

[0003] The film for auto uses an automatic wrapping machine. For example, the film is fed out with a conveyor belt, and a saw-shaped cutting blade provided between the conveyor belts is protruded and perforated to convey the film. Cut it. Thereafter, the central portion of the cut film is pushed up and stretched by a tray on which food is placed, and the film is folded and overlapped by a folding plate. For this reason, it is particularly required that the film be perforated neatly, that the film be stretched and not broken when it is folded and that the film be not easily peeled off after being stacked.

On the other hand, a hand film is manually formed by a packaging worker using a hand wrapper.
Grasp the end of the film placed on the payout roll with both hands, pay out the film of the length necessary to cover the entire tray on which the food on the workbench is placed, and after covering the entire tray,
The film is cut with a hot wire, then the covered film is stretched laterally, the films are overlapped at the bottom of the tray, and then the joined parts are heat sealed. When performed manually, the film can be unwound smoothly, the operator can easily stretch it, it does not get tired even if packaging is continued for a long time, it does not break when stretched, and it is hard to peel off when stacking films, and it is easy to heat seal For example, performance different from that of the film for auto is required.

As a stretch film for a hand used for food packaging, a polyvinyl chloride (hereinafter referred to as "PVC") type stretch film has been mainly used. This is because the film has good transparency, it is easy for workers to stretch and it is hard to get tired, the finish is clean without wrinkles, etc. In addition to deformation suitability, it recovers without leaving wrinkles against deformation on the film surface And the peeling of the overlapping portion of the stretch film bottom during transport and display is less likely to occur.
This is because it has the superiority of quality that has been recognized by both sellers and consumers that the product value does not decrease.

However, in recent years, problems such as hydrogen chloride gas generated during incineration of a PVC-based stretch film and elution of a contained plasticizer have been regarded as problems. For this reason, olefin-based stretch films have been studied and used as alternatives to PVC.

[0007] As an olefin-based stretch film for a hand, a layer mainly composed of a thermoplastic elastomer having excellent deformation recovery properties is used to impart tackiness to an ethylene-based layer.
Many multilayer films in which a vinyl acetate copolymer is laminated are provided.

[0008] The film is produced by cutting both ends, so-called ears, of an extra film at the time of film formation. Ears are returned to at least one layer in the case of a multilayer film to increase the raw material yield as scrap. However, since the middle layer and the resin having different surface layers are mixed in the ears of the multilayer film, the transparency and strength of the film generally decrease when the ears are returned to a single layer in the film as scrap. Therefore, there is a problem that the scrap cannot be returned, or the amount of scrap returned is limited and the yield does not increase.

On the other hand, a film having a single-layer structure does not have the above-mentioned problems, and an olefin-based stretch film using a high-pressure process polyethylene and an ethylene / α-olefin copolymer resin is disclosed in Japanese Patent Application Laid-Open No. 52-84096. Showa 59
49248, JP-A-4-91148, JP-A-8-3
384 and Japanese Patent Application Laid-Open No. 11-228758. However, when such a single-layer olefin-based stretch film is used for a hand, there is a problem that the elongation is low, the finish of the package is wrinkled, and the adhesiveness is not sufficient. Further, there is a problem of film forming property that the width of the film coming out of the die during the production of the film fluctuates as it expands and contracts.

[0010]

SUMMARY OF THE INVENTION The present invention provides a stretch film which is excellent in film-forming properties, has good transparency, and has appropriate elongation and adhesiveness particularly suitable for hand wrap packaging.

[0011]

That is, the present invention provides a linear low-density polyethylene (A) having a density exceeding 910 kg / m3, a linear low-density polyethylene (B) having a density of 910 kg / m3 or less, and a high-pressure method. Polyethylene (C) is contained, and based on the total of (A), (B) and (C),
(A) 90 to 20% by weight, (B) 5 to 40% by weight and (C) 5 to 40% by weight of a stretch film for a hand. More preferably, 0.5 to 10 parts by weight of petroleum resin, terpene, terpene derivative, rosin, rosin derivative and hydrogenated product thereof with respect to the total of (A), (B) and (C). It is a stretch film for hand wraps to which at least one is added.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The linear low density polyethylene (A) used in the present invention has a density of 910 kg / m3, preferably 915 kg / m3.
And generally called LLDPE. Among them, a copolymer of ethylene and an α-olefin is preferable. As the α-olefin, propylene,
Butene-1, hexene-1, 4-methylpentene-1,
Hexene-1, heptene-1, octene-1, nonene-
1, decene-1, dodecene-1 and the like, preferably,
The α-olefin has 6 to 8 carbon atoms. Carbon number 6 ~
The ethylene / α-olefin copolymer film No. 8 has a high tensile strength and is not easily broken at the time of film stretching. A commercially available linear low-density polyethylene (A) can be used.

The amounts of (A) are (A), (B) and (C)
Is preferably 90 to 20% by weight based on the total of If it exceeds 90% by weight, the transparency of the film becomes poor. In addition, the film becomes hard and cannot be stretched with an appropriate strength, so that the film is easily fatigued by the operator. On the other hand, if it is less than 20% by weight, the tensile strength of the stretch film is low, and the stretch film tends to be broken during stretching.

The linear low-density polyethylene (B) used in the present invention has a density of not more than 910 kg / m3, preferably not more than 910 kg / m3 and not less than 880 kg / m3, generally called VLDPE. is there. Among them, a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms is preferable. Specific examples of the α-olefin include propylene, butene-1, hexene-1, 4-methylpentene-
1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, dodecene-1 and the like. A commercially available linear low-density polyethylene (B) can be used.

The amount of (B) is preferably from 5 to 40% by weight. If the amount is less than 5% by weight, the adhesiveness of the film becomes weak, and the unwinding of the film becomes too light. Also, before heat sealing the part where the films are overlapped at the bottom of the tray, the stretched film comes off and returns to its original position,
Cannot be heat sealed. On the other hand, if it exceeds 40% by weight, does the film become too sticky, causing a so-called "blocking" in which the film sticks and does not come off when formed into a roll, making it difficult to repeat when using the film? In some cases, it will not be possible to feed out. In the present invention, it is preferable to make the amount of (A) larger than that of (B) in order to give the film firmness.

The high-pressure polyethylene (C) of the present invention is produced by a high-pressure radical polymerization method, and a commercially available product can be used. The amount of (C) added is 5 to 4
0% by weight is preferred. If it is less than 5% by weight, the melt tension becomes low and the film width fluctuates. On the other hand, if it exceeds 40% by weight, the film strength is reduced, and the film tends to be broken during stretching.

The present invention provides a commercially available C5 component as the component (D).
(Aliphatic), C9 (aromatic), C5C9 copolymer or cyclopentadiene petroleum resins and their hydrogenated products, or terpenes, terpene derivatives, and their hydrogenated rosins, rosin derivatives and their It is preferable to add at least one of the hydrogenated products described above. The component (D)
A plurality of components selected from the above can be added. By adding these, it is possible to increase the strength at the time of stretching the film and to impart tackiness to the film, and it is easy to simultaneously satisfy several required performances as a stretch film for a hand. The added amount of the component (D) is preferably 0.5 to 10 parts by weight based on the total of (A), (B) and (C). If the amount is less than 0.5 part by weight, the effect of improving the ease of tearing during film stretching is hardly observed. On the other hand, when the amount exceeds 10 parts by weight, when the resin raw material is introduced into the extruder at the time of film formation, the resin does not bite well and it is difficult to stably produce the film.
Also, on the other hand, the adhesiveness of the formed film is too strong, and when the film is wound up, `` blocking '' occurs, or it becomes difficult to feed out when using the film,
In some cases, it will not be possible to feed out.

It is preferable to add an antifogging agent to the stretch film of the present invention. The addition amount is 1 to 5%, preferably 1.5 to 4%. Examples of the antifogging agent include surfactants conforming to the PL standard (list of food additives), such as glycerin fatty acid (C8-22) ester, sorbitan fatty acid (C8-22) ester, propylene glycol fatty acid (C8-22) ester, Sugar fatty acids (C8-2
2) esters, citric acid mono (di or tri) stearic acid esters, pentaerythritol fatty acids (C8-2
2) Ester, polyglycerin fatty acid (C8-22) ester, polyoxyethylene (20) glycerin fatty acid (C8-22) ester, polyethylene glycol fatty acid (C8-22) ester, polypropylene glycol fatty acid (C8-22) ester, poly Oxyethylene (9.5) dodecyl ether, polyoxyethylene (4
-14.30-50) alkyl (C4, 9, 12) phenyl ether, condensation product of N, N-bis (2) -hydroxyethyl fatty acid (C12-18) with diethanolamine, polyoxypropylene polyoxyethylene block Polymer, polyethylene glycol (molecular weight 20
0-9500), polypropylene glycol and the like.

The stretch film of the present invention may contain, if necessary, a stabilizer, an antistatic agent, and a processability improver. For example, 2,6-di-t-butyl-p-cresol (BHT), tetrakis [methylene-3-
(3,5-di-tbutyl-4-hydroxyphenyl) propionate] methane, n-octadecyl-3- (4 ′
Phenolic stabilizers represented by -hydroxy-3,5'-di-t-butylphenyl) propionate, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite and tris (2,4- Phosphite stabilizers represented by di-t-butylphenyl) phosphite, etc .; antistatic agents such as glycerin esters, sorbitanate esters and polyethylene glycol esters of fatty acids having 8 to 22 carbon atoms; fatty acid metals such as calcium stearate A processability improver represented by a salt can be added.

The thickness of the stretch film of the present invention is in the range used as a normal stretch film, ie, 5
About 30 μm, preferably about 8 to 20 μm.

The method for producing the stretch film for a hand of the present invention is not particularly limited. Although a known method can be used, a T-die method is preferable. The T-die method is
Compared with the inflation method, the molten resin can be rapidly cooled by a cooling roll, so that the crystallinity of the film can be suppressed and the transparency can be improved. In addition, the film thickness accuracy is high, and the production speed is superior to the inflation method. In the stretch film of the present invention, scraps such as ears generated during film formation can be returned without any trouble. This is because the scrap contains no components other than the components used. When the scrap is returned, the transparency and strength of the film do not decrease, and the generation of gel or the like does not matter.

[0022]

The present invention will be described in more detail with reference to the following examples. The properties and properties of the raw materials used and the stretch film were measured and evaluated by the following methods.

1) Density Measured according to JIS K6760. 2) Melt flow rate (MFR) Measured according to JIS K6760. The values are 190 ° C. and a load of 2.16 kg. 3) Transparency (Haze%) Measured in accordance with ASTM-D1003. 4) Hand wrapping property A 300mm wide film can be handled with a hand wrapper (ARC
After passing the paper through POLYWRAPPER 40, the film edge is gripped with both hands and the film is fed out. Cover the entire tray with the food on the workbench with the unwound film, and cut the film with a hot wire. The covered film is stretched in the horizontal direction, and the films are overlapped at the bottom of the tray, and then heat-sealed. Based on the criterion shown in Table 3, the film was evaluated for its dispensing property, elongation, tear, adhesiveness, and wrinkles at the time of packaging.

(Example 1) An ethylene / α-olefin copolymer having a density of 913 kg / m 3 and an α-olefin having 6 carbon atoms (MFR = 2.0 190 ° C, 2.16 kg)) 5
0% by weight, an ethylene / α-olefin copolymer (MFR) having a density of 900 kg / m 3 as a linear low-density polyethylene (B) and an α-olefin having 4 carbon atoms
= 2.0 (190 ° C, 2.16 kg)) 25% by weight and density 924 kg / m3 High pressure method polyethylene (C)
(MFR = 2.0 (190 ° C., 2.16 kg)) A composition obtained by adding 2 parts by weight of diglycerin monooleate as an anti-fogging agent to 25% by weight was molded by a T-die method to have a thickness of 12 μm.
m stretch film was produced.

The molding conditions were as follows: (A), (B) and (C) were dry-blended, and the mixture was subjected to L-shape extrusion using a 65 mm single screw extruder manufactured by Toshiba Machine Co.
Using a full-flight screw of / D = 28, using a T-die having a die width of 550 mm and a die lip of 0.7 mm, a take-up speed of 60 m / min at a set temperature of 180 ° C. to 230 ° C.

(Examples 2 and 3) A stretch film was produced by using the same resin as in Example 1 and changing the ratio as shown in Table 1.

Example 4 The ethylene / α-olefin copolymer (A) of Example 1 having a density of 920 kg / m 3 and an α-olefin having 6 carbon atoms was prepared.
Olefin copolymer (MFR = 2.0 (190 ° C., 2.
A film was produced in the same manner as in Example 1 except that the film was changed to 16 kg)).

Example 5 The ethylene / α-olefin copolymer (A) of Example 1 having a density of 919 kg / m 3 and an α-olefin having 4 carbon atoms was prepared.
Olefin copolymer (MFR = 2.0 (190 ° C., 2.
A film was produced in the same manner as in Example 1 except that the film was changed to 16 kg)).

Example 6 As a linear low-density polyethylene (A), an ethylene / α-olefin copolymer having a density of 913 kg / m 3 and an α-olefin having 6 carbon atoms (MFR = 2.0 190 ° C, 2.16 kg)) 5
0% by weight, an ethylene / α-olefin copolymer (MFR) having a density of 900 kg / m 3 as a linear low-density polyethylene (B) and an α-olefin having 4 carbon atoms
= 2.0 (190 ° C., 2.16 kg)) 25% by weight, density 924 kg / m 3 high pressure method polyethylene (C) (M
FR = 2.0 (190 ° C., 2.16 kg)) 25% by weight
And hydrogenated petroleum resin (softening point 125 ° C) as component (D)
5 parts by weight and 2 parts of diglycerin monooleate as an anti-fog agent
The composition added by part by weight is molded to a thickness of 1 by the T-die method.
A 2 μm stretch film was produced.

(Examples 7 and 8) Stretch films were produced by using the same resins as in Example 6 and changing the ratios as shown in Table 1.

Example 9 The ethylene / α-olefin copolymer (A) of Example 6 was prepared by mixing ethylene / α-olefin having a density of 919 kg / m 3 and an α-olefin having 4 carbon atoms.
Olefin copolymer (MFR = 2.0 (190 ° C., 2.
A film was produced in the same manner as in Example 6, except that the film was changed to 16 kg)).

Comparative Examples 1 to 4 Stretch films were produced by using the same resins as in Example 1 and changing the ratios as shown in Table 2.

Comparative Example 5 The ethylene / α-olefin copolymer (B) of Example 1 having a density of 919 kg / m 3 and an α-olefin having 4 carbon atoms was prepared.
Olefin copolymer (MFR = 2.0 (190 ° C., 2.
A film was produced in the same manner as in Example 1 except that the film was changed to 16 kg)).

(Comparative Examples 6 to 10) Stretch films were produced by using the same resins as in Example 6 and changing the ratios as shown in Table 2.

(Comparative Example 11) The ethylene • α-
The olefin copolymer (B) is ethylene • α having a density of 919 kg / m 3 and an α-olefin having 4 carbon atoms.
-Olefin copolymer (MFR = 2.0 (190 ° C,
A film was produced in the same manner as in Example 6 except that the film thickness was changed to 2.16 kg)). Properties about these films,
Tables 1 and 2 show the performance evaluation results.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

The stretch film for hand wraps of the present invention has good transparency, is excellent in suitability for hand wrap packaging, and particularly has moderate elongation and adhesiveness.

Continued on the front page F term (reference) 4F071 AA18 AA19 AA39 AA71 AH04 BB06 BC01 4J002 AE05Z AF02Z BA01Z BB03W BB03X BB03Y BB05W BB05X BK00Z FD030 FD100 FD200 GG02

Claims (4)

[Claims] 1. It comprises a linear low-density polyethylene (A) having a density exceeding 910 kg / m3, a linear low-density polyethylene (B) having a density of 910 kg / m3 or less, and a high-pressure polyethylene (C). , (A) 90 to 20% by weight based on the total of (A), (B) and (C),
(B) 5 to 40% by weight and (C) 5 to 40% by weight of a stretch film for hand wrap. 2. 0.5 to 10 parts by weight of petroleum resin, terpene, terpene derivative, rosin, rosin derivative and water thereof as component (D) based on the total of (A), (B) and (C). The stretch film for hand wrap according to claim 1, wherein at least one of the additives is added. 3. The linear low-density polyethylene is an ethylene / α-olefin copolymer, and the ethylene / α-olefin copolymer of the linear low-density polyethylene (A) has a carbon number of α-olefin. The stretch film for hand wrap according to claim 1 or 2, which is 6 to 8. 4. The method according to claim 1, wherein the semiconductor device is manufactured by a T-die method.
Or the stretch film for a hand wrap according to claim 3.