JPH07173612A - Twist wrapping - Google Patents

Abstract

PURPOSE:To improve the twist holding property and solvent releasability by coating the surface of the PP film contg. a specified amt. of petroleum resin, etc., with the double bond eliminated by hydrogenation. CONSTITUTION:The twist-wrapping film to be printed with use of an oleophilic solvent is obtained by coating one side of a biaxially oriented PP film, and the solvent releasability in printing is improved. The PP film contains 15-30wt.% of the petroleum resin with the double bond eliminated by hydrogenation or terpene resin. Besides, the coating is conducted by vacuum deposition, and the coaling layer consists of polyvinylidene chloride.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a twist packaging film having excellent twist holding property.

[0002]

2. Description of the Related Art Cellophane as a film for twist packaging,
A uniaxially stretched high density polyethylene film or the like is used. However, these films have drawbacks such as easy tearing.

The biaxially oriented polypropylene film is a film excellent in mechanical properties, moisture resistance, transparency, etc., but is not suitable at all in terms of twist holding property.

When a petroleum resin or the like is used as a modifier of polypropylene, the twistability is improved in addition to transparency and moisture resistance, but the solvent of the ink is likely to remain during printing of this film.

[0005]

[Problem to be Solved by the Invention] Twist packaging film is improved in tearability, and twistability and printability are imparted while maintaining the excellent properties of biaxially oriented polypropylene.

[0006]

Means for Solving the Problems The inventors of the present invention have made various investigations to solve the above-mentioned problems, and have solved the problems by the following method.

Twistability was exhibited by adding petroleum resin or terpene resin to polypropylene in an amount of 15% by weight or more. The polypropylene mentioned here refers to crystalline polypropylene, a copolymer thereof, or a mixed system of both. Petroleum resin is an alicyclic petroleum resin that does not contain a double bond in the molecule and is compatible with polypropylene.
Good in terms of weather resistance. Further, if the amount of petroleum resin added is less than 15% by weight, twisting aptitude is not expressed, and if it is too large, there is a problem in moldability, so a range of 15 to 30% by weight is preferable.

[0008] As a method for improving the solvent removability without impairing the twisting suitability, a method of coating aluminum, silicon oxide or the like by a vacuum deposition method, or coating a high density polyethylene or non-oriented polyolefin having twisting suitability itself I found a way to do it. In the latter case, the coextrusion method is preferable because of the manufacturing cost. In order to make it non-oriented, a coat resin that can be melted at a temperature that does not melt the stretched polypropylene is selected, and the orientation of the coat resin is extinguished by heating and melting after biaxial stretching. It was also found that the polyvinylidene chloride coat having a high barrier property is excellent not only in solvent resistance but also in the twist suitability.

[0009]

EXAMPLES The examples described below are preferred examples for clarifying the character of the present invention, and are not limited to these examples.

[0010]

Example 1 A petroleum resin hydrogenated to crystalline polypropylene (ESCOLETS 356B manufactured by Exxon Co.) was extruded into a film with a T-die extruder at a mixing ratio shown in Table 1.
After stretching 5 times at 20 ° C. and then 10 times in the transverse direction at 160 ° C., heat treatment was performed at 170 ° C. to obtain a stretched film having a thickness of 25 μm. The results of measuring the twisting suitability of the film are shown in Table 1. The twist aptitude given here is 2 after wrapping the film in a certain volume and wrapping it with a clip.
Evaluation was carried out under the condition that the product was rotated and twisted and held for one hour.

Next, the product of the petroleum resin addition amount of 23% by weight in Table 1 is designated as A, and uniaxially stretched high density polyethylene (OP)
Table 2 shows the results of the actual packaging test of E) and cellophane using a twist packaging machine. The test conditions were two rotations of the twist claw and 110 shots / min. The evaluation method was a value obtained by dividing the number of rotations of the twist after being left for 24 hours by 2 (twist retention rate), the tear rate of the packaged film at that time (tear rate), and after rotating in a ball mill for 1 hour. The rate of dropout of the package (dropout rate) and the appearance during the drop test were evaluated. Although the twist retention rate of A is slightly lower than that of cellophane, it is on par with that of O-PE and practically sufficient results were obtained. In addition, although the dropout rates are all about the same, the appearance at that time is very good compared to the other two, and the shape of the ears of the twisted package (the part to be held by hand when opening the package) is retained. Was. With respect to the tear rate, O-PE caused tears during horizontal twisting, but A did not tear at all.

A film obtained by coating aluminum with 500Å aluminum by vacuum vapor deposition is designated as B, and a film similarly coated with 300Å silicon oxide (SiO _1.8 ) is designated as C. Next, methyl methacrylate is added to A in the molecule 1
A film coated with a polyvinylidene chloride emulsion containing 0% by weight to a thickness of 1 μm is designated as D. When these were also examined for twisting suitability, a good twisting retention rate was shown regardless of the presence or absence of coating treatment.

Further, the solvent residual property is greatly improved by coating the surface. The residual solvent properties of the films A to D were printed with a solution of 20% by weight of toluene added to the ink (Lamiter R63S manufactured by Toyo Ink Co., Ltd.), and dried for 5 seconds by applying hot air at 50 ° C. Next, the toluene content of this film was measured and evaluated by gas chromatography.

[0014]

Example 2 A terpene resin (Clearon B-140 manufactured by Yasuhara Yushi Kogyo KK) was mixed with crystalline polypropylene in an amount of 20% by weight, and a biaxially stretched film having a thickness of 25 μm obtained in the same manner as in Example 1 was designated as E. A biaxially stretched film having a total thickness of 25 μm, in which E was used as an intermediate layer, and crystalline polypropylene, polypropylene copolymer (mp = 140 ° C.) and high density polyethylene were laminated on both sides by 1 μm on both sides by a co-extrusion method. Let them be F, G, and H, respectively. Since the surface layer portions of G and H were heated above the melting point, the orientation disappeared. Table 4 shows the results of measuring the twisting aptitude and the solvent retention of these.

[0015]

INDUSTRIAL APPLICABILITY The film of the present invention can be imparted with twisting aptitude while retaining the excellent properties of a biaxially oriented polypropylene film and without greatly increasing the residual solvent at the time of printing.

[Short description of table]

[Table 1] It is explanatory drawing which showed the relationship between petroleum resin concentration and twist suitability.

[Table 2] It is explanatory drawing which showed the packaging test result of the biaxially-stretched polypropylene film (A) for twist packaging and a general twist packaging film.

[Table 3] It is explanatory drawing which showed the relationship between A which gave surface treatment, twist suitability, and residual solvent property.

[Table 4] It is explanatory drawing which showed the relationship between the twisted biaxial polypropylene film for twist packaging, twist aptitude, and solvent retention.

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Claims (5)

[Claims] 1. A biaxially oriented polypropylene film containing 15 to 30% by weight of a petroleum resin or terpene resin in which hydrogen has been added to eliminate a double bond is subjected to a coating treatment for improving solvent releasing property at the time of printing. , Twist packaging using film printed with lipophilic solvent 2. When the above coating is performed by vacuum vapor deposition 3. The case where the coating layer is polyvinylidene chloride 4. The above-mentioned coat layer is a high-density polyethylene formed by co-extrusion. 5. The case where the coating layer is a non-oriented polyolefin formed by co-extrusion