JP2006224678A - Manufacturing process of cyclic polyolefin based heat-shrinkable tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cyclic polyolefin heat shrinkable tube, which can set a printed face on the inside surface of its film, is excellent in the appearance of the surface of the junction for forming a tube, and is excellent in bonding strength, too. <P>SOLUTION: The cyclic polyolefin heat shrinkable tube is obtained by center-sealing a flat heat shrinkable film with an organic solvent. An organic solvent blend, containing at least one solvent which has a transformation ratio of 1 to 30% and at least one which has a transformation ratio of less than 1%, is preferred as the organic solvent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-shrinkable tube which is beautiful, has a waist and is heat-shrinkable in the circumferential direction, and particularly useful as a label or cap seal.

  A heat-shrinkable film made of a cyclic polyolefin-based resin is excellent in transparency and gloss, and has an appropriate waist, so that it has been variously studied as a packaging material. For example, in Patent Document 1, a mixture of cyclic polyolefin resin (A) and olefin resin (B) in a weight ratio of A / B = 60 to 50/40 to 50 is extruded into a tube shape by a circular die, and this is extruded. A heat-shrinkable cyclic polyolefin tube suitable for coating a battery or the like by tubular stretching is disclosed. Moreover, in patent document 2, the layer which consists of a mixture of a linear low density polyethylene and cyclic polyolefin-type resin is used, and the layer which consists of a composition which has a linear low density polyethylene as a main component is made into an innermost layer and an outermost layer. Disclosed is a heat-shrinkable coextruded film that is stretched by tubular stretching of a tubular unstretched film and is excellent in heat sealability and suitable for pillow packaging.

JP-A-9-278974 JP-A-8-267679

  In order to convey information such as product names and precautions for use and to provide design, there are many cases where printing is performed on the inner surface side of a transparent plastic packaging material. The reason for printing on the inner surface side is to prevent printing ink peeling due to rubbing and to improve the appearance due to the gloss of the plastic. However, since each of the above-mentioned publications uses a tubular method, printing cannot be performed on the inner surface side of the film.

  To obtain a heat-shrinkable tube with printing on the inner surface side of the film, fold a pre-printed flat heat-shrinkable film so that the printing surface is inside, and center seal (the shape of the seal part is a so-called envelope) And it may be tube-shaped. As the center sealing method, a heat sealing method, an adhesive method, and an impulse sealing method can be considered.

  However, in the heat sealing method, the sealing portion is shrunk by heat, so that a good-looking cyclic polyolefin heat-shrinkable tube cannot be obtained.

  In addition, in the method using an adhesive (for example, urethane-based adhesive), it is difficult to apply the adhesive stably, so whether the processing speed is reduced to 50 to 70 m / min and the application can be normally performed. It needs to be monitored closely by people. In addition, since it is necessary to confirm whether the adhesive force of the obtained center seal part is normal or not after the adhesive is almost completely cured, after about 12 hours or more, usually 24 hours have passed after the center seal. There is a problem that can not be done. Further, since the adhesive does not have heat shrinkability, the sealing strength after the obtained cyclic polyolefin heat shrinkable tube is heat-shrinked and attached to the container is lowered. For this reason, there exists a problem that a seal | sticker part peels easily at the heating process received after that, ie, heat treatment processes, such as hot filling of a content product, a boil process, a retort process. In addition, the method of center sealing with ultrasonic waves has a drawback that the processing speed is as slow as 30 to 50 m / min, and the sealing portion is wavy and looks bad.

  A first problem to be solved by the present invention is a cyclic polyolefin heat-shrinkable tube having a printing surface on the inner surface side of the film, a bonding surface for forming a tube having an aesthetic appearance, and excellent bonding strength. It is to provide.

  A second problem is to provide a cyclic polyolefin heat-shrinkable tube having heat-shrink characteristics, particularly heat-shrink characteristics suitable for labels and cap seals.

  The third problem is to provide a method for producing a cyclic polyolefin heat-shrinkable tube having excellent processing speed and stable productivity.

  A fourth problem is to provide a container equipped with a cyclic polyolefin heat-shrinkable tube that is beautiful and excellent in bonding strength.

  As a means for solving the above-mentioned problems, the present invention provides a flat heat-shrinkable film as an organic solvent, preferably at least one kind having a deformation rate of 1 to 30% and at least one kind having a deformation rate of less than 1%. A cyclic polyolefin-based heat-shrinkable tube having a center seal with a mixed organic solvent contained and having a seal strength of the center seal portion of 100 g / cm or more is obtained.

  A cyclic polyolefin heat-shrinkable tube having a heat shrinkage rate of 20% or more in the circumferential direction and a heat shrinkage rate of 10% or less in a direction orthogonal to the circumferential direction at 80 ° C. × 10 seconds.

  Further, a step of center sealing with an organic solvent at a processing speed of 80 to 150 m / min is provided.

  Furthermore, it is set as the container equipped with the above-mentioned cyclic polyolefin heat shrinkable tube.

  Since this invention consists of the above structures, there exists an effect as described below.

  The printing surface is on the inner surface of the film, the sealing surface for forming the tube is excellent in aesthetics, and the sealing strength is also excellent. Furthermore, by specifying the thermal shrinkage rate in the circumferential direction and the direction perpendicular to the circumferential direction, it becomes particularly useful as a label or cap seal.

  Embodiments of the present invention will be described in detail below.

  The cyclic polyolefin of the present invention is a general generic name. Specifically, (a) a ring-opening (co) polymer of a cyclic olefin is modified as necessary, such as addition of maleic acid or cyclopentadiene. Thereafter, a hydrogenated polymer, (b) an addition polymer of a cyclic olefin, and (c) an addition copolymer of a cyclic olefin and an α-olefin such as ethylene or propylene. Examples of cyclic olefins include norbornene and tetracyclododecene.

  Any known production method may be used for obtaining a flat cyclic polyolefin-based heat-shrinkable film. For example, the cyclic polyolefin is extruded from a T die, rolled in the machine direction 1 to 2 times (meaning that 1 time is not stretched), stretched in the transverse direction 2 to 10 times, and stretched 0 to 0 in the width direction. A method obtained by annealing while relaxing 10% can be exemplified. Next, the film is slit to a predetermined width and printed on one side of the film by an appropriate method such as gravure printing. At this time, one end portion of the film serving as a seal allowance is a printed design that becomes a non-printing portion.

  In order to obtain a tube from the flat heat-shrinkable film thus obtained, the present invention performs center sealing with an organic solvent. This center seal processing will be described with reference to FIG. FIG. 1 is a simplified diagram showing a typical center seal processing method. 1 is a flat cyclic polyolefin heat-shrinkable film folded at both ends in an envelope shape, and 2 is a cyclic polyolefin heat-shrink film formed by center sealing. 3 is a center seal portion, 4 is a seal margin, 5 is a nozzle for applying an organic solvent, and 6 is a nip roll. The film travels in the direction of the arrow in FIG. 1, an organic solvent is applied from the nozzle 5 to the seal margin 4, and is pressure-bonded by the nip roll 6 to obtain a cyclic polyolefin heat-shrinkable tube. The speed of the center seal is 80 to 150 m / min, preferably 120 to 140 m / min.

  The organic solvent used is at least one organic solvent. Preferably, it is an organic solvent having a deformation rate of 1 to 30%, more preferably 3 to 15% according to the measurement method described later. When the deformation rate is 1% or more, the seal strength (joint strength) of the center seal portion (joint portion) is increased, and a preferable result is obtained. If the deformation rate exceeds 30%, the seal portion will be wavy and the appearance will be poor, and the heat shrinkage rate of the seal portion will also be reduced, so there will be a difference in the heat shrinkage rate with parts other than the seal portion, and the container When heat shrinkage is applied to the film, the film is distorted, which tends to be undesirable. Examples of those having a deformation rate of 1 to 30% include tetrahydrofuran (deformation rate: 8 to 13%), n-pentane (deformation rate: 5 to 11%), and n-hexane (deformation rate: 5 to 10%). Examples thereof include C5-C10 aliphatic hydrocarbons.

  More preferably, a mixed solvent containing at least one (A) having a deformation rate of 1 to 30% (most preferably 3 to 15%) and at least one (B) having a deformation rate of less than 1% is used. . When such a mixed solvent is used, since there is a difference in the attack strength of each solvent to the film, a more preferable (most preferable) result can be obtained in terms of center seal stability, beautifulness of the seal surface, seal strength, and the like. . A preferable mixing ratio is (A) / (B) = 99-50 / 1-50 by weight.

  Examples of those having a deformation rate of less than 1% include acetone (deformation rate: about 0%), methyl acetate (deformation rate: about 0%), ethyl acetate (deformation rate: about 0%), 1,3-dioxolane. (Deformation rate: about 0%) and isopropyl alcohol (deformation rate: about 0%) can be exemplified. In addition, the organic solvent may contain a small amount of resin.

  The center seal portion thus obtained has a seal strength of 100 g / cm or more, preferably 400 g / cm or more, and does not peel off in heat treatment processes such as hot filling, boil treatment, retort treatment, etc., and there is no waviness on the seal surface. It has a good appearance.

  A cyclic polyolefin heat-shrinkable tube has a heat shrinkage rate in the circumferential direction at 80 ° C. × 10 seconds of 20% or more, preferably 30% or more, and a heat shrinkage rate in a direction perpendicular to the heat shrinkage rate of 10% or less, preferably 3 % Or less, it becomes a preferable tube as a label or cap seal. When the heat shrinkage rate in the circumferential direction is less than 20%, it tends to be difficult to finish tightly when heat shrinkage is applied to a plastic bottle, a glass bottle or the like. On the other hand, if the thermal shrinkage in the direction perpendicular to it exceeds 10%, vertical shrinkage occurs, and it is difficult to obtain a beautiful finish. In order to obtain such a heat shrinkage rate, various conditions when producing a flat cyclic polyolefin heat shrinkable film, such as the stretching ratio in the machine direction and the transverse direction, the stretching temperature, the annealing temperature, the relaxation rate, etc. What is necessary is just to select suitably.

  The cyclic polyolefin-based heat-shrinkable tube may be a tube made of a single layer cyclic polyolefin, or may be a multi-layer tube made of different cyclic polyolefins. Moreover, another resin layer may be included. The cyclic polyolefin may be mixed with other resins for the purpose as long as the center seal characteristics are not impaired.

  The container referred to in the present invention means not only plastic bottles and glass bottles but also various molded containers and other containers to which the heat-shrinkable tube of the present invention can be applied.

  Next, typical examples of the present invention will be described.

  The deformation rate is determined by the following method. That is, a sample was cut out from a flat cyclic polyolefin-based heat-shrinkable film in the lengthwise direction × widthwise direction = 30 mm × 100 mm, immersed in an organic solvent in a beaker for 1 minute, taken out, and immediately taken out in the transverse length L ′. (Mm) is measured. This measurement is repeated for 10 samples, and the average value L of L ′ is calculated. And 100-L was made into the deformation rate of this organic solvent.

  The seal strength of the center seal portion is as follows. That is, a sample is cut out from the cyclic polyolefin heat-shrinkable tube to a width of 1 cm in the circumferential direction. Next, the seal margin part of the seal part and the end part of the other piece were respectively set on a HEIDON-17 type peel tester manufactured by Shinto Kagaku Co., Ltd. and measured at a peel rate of 20 cm / min.

The heat shrinkage rate of the cyclic polyolefin heat-shrinkable tube is as follows. That is, a sample is cut out in the circumferential direction × the direction orthogonal thereto = 100 mm × 100 mm. Next, the sample was immersed in a hot water bath at 80 ° C. for 10 seconds, immediately cooled with cold water, and the lengths l ₁ ′ (mm) and l ₂ ′ (mm) in the circumferential direction and the direction perpendicular thereto were measured. To do. This measurement is repeated with 10 samples, and average values l ₁ and l ₂ of l ₁ ′ and l ₂ ′ are calculated. 100-l ₁ was the heat shrinkage rate in the circumferential direction, and 100-l ₂ was the heat shrinkage rate in the direction orthogonal thereto.

Example 1
Petroleum resin (Arakawa Chemical Co., Ltd.) in 100 parts by weight of cyclic polyolefin (Apel APL8008T manufactured by Mitsui Chemicals, Inc.) serving as the A layer and C layer and ethylene-propylene random copolymer (F233D manufactured by Grand Polymer Co., Ltd.) serving as the B layer A mixture of 50 parts by weight of Alcon P-125, manufactured by Kogyo Co., Ltd., was put into separate extruders and extruded from a T-die at 240 ° C. so as to form a laminate of A / B / C. After cooling and solidifying with a 40 ° C cooling roll, the film was stretched 1.2 times in the machine direction at 90 ° C, stretched 4 times in the transverse direction at 85 ° C, and then relaxed 5% in the width direction in the same tenter. Then, the film was annealed at 70 ° C. for 5 seconds to obtain a flat heat-shrinkable film. As for the thickness of this film, the A layer was 6 μm, the B layer was 48 μm, the C layer was 6 μm, and the total thickness was 60 μm.

  The obtained film was slit to a width of 770 mm with a slitter machine, and then 5 colors were printed on one side of the film with a gravure printer. Three printed designs were taken in the width direction of the film, and each one end portion (being a seal margin) was a non-printing portion. Next, it was slit into 3 with a slitter machine. Next, using a mixed solvent obtained by mixing 90 parts by weight of tetrahydrofuran (deformation rate: 10%) and 10 parts by weight of isopropyl alcohol (deformation rate: 0%) as an organic solvent, a processing speed of 130 m / m as shown in FIG. Center sealed in minutes. The seal margin at this time was 4 mm wide. The seal strength of the center seal portion of the cyclic polyolefin heat shrinkable tube thus obtained was 500 g / cm. Further, the heat shrinkage rate in the circumferential direction was 33%, and the heat shrinkage rate in the direction perpendicular thereto was 2%.

Next, the tube is cut into a length of 80 mm to form a label, which is covered with a PET bottle, and heat-shrinked at 80 ° C. for 5 seconds using a wet heat type shrink tunnel (length 3 m, vapor pressure 0.3 kg / cm ² ). It was. The label was tightly attached to the bottle, had no vertical draw, and was beautiful without wrinkles or avatars.

It is a simplified diagram showing a typical center seal processing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flat cyclic polyolefin-type heat-shrinkable film 2 Cyclic polyolefin-type heat-shrinkable tube 3 Center seal part 4 Seal cost 5 Nozzle which applies organic solvent 6 Nip roll

Claims (6)

  A cyclic polyolefin-based heat-shrinkable tube formed by center-sealing a flat heat-shrinkable film with an organic solvent.   The cyclic polyolefin heat-shrinkable tube according to claim 1, wherein the organic solvent is a mixed organic solvent containing at least one kind having a deformation rate of 1 to 30% and at least one kind having a deformation rate of less than 1%.   The cyclic polyolefin heat-shrinkable tube according to claim 1 or 2, wherein the seal strength of the center seal portion is 100 g / cm or more.   The cyclic polyolefin heat according to any one of claims 1 to 3, wherein a heat shrinkage rate in the circumferential direction at 80 ° C x 10 seconds is 20% or more and a heat shrinkage rate in a direction perpendicular thereto is 10% or less. Shrinkable tube.   A method for producing a cyclic polyolefin heat-shrinkable tube, comprising a step of center sealing with an organic solvent at a processing speed of 80 to 150 m / min.   A container equipped with the cyclic polyolefin heat-shrinkable tube according to any one of claims 1 to 5.

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