JP2001328221A - Easy opening packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy opening packaging material excellent in blocking properties at the time of winding or the like. SOLUTION: The easy opening packaging material comprises at least two thermoplastic resin layers each having a base layer and a seal layer. When seal layers are superposed one upon another to be allowed to stand at 50 deg.C for 72 hr while a load of 25 kg is applied to the seal layers per an area of 100 mm2 and the seal layers are subsequently peeled at a speed between chucks of 200 mm/min, the peel strength of the seal layers is 1 N/100 mm or less. As the seal layer, a low crystalline polyester layer is used and, as the base layer, a modified polyolefin layer is used. This easy opening packaging material is low in blocking strength and can be prevented from blocking even if it is wound and has a wide heat seal temperature range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-opening (easy peeling) packaging material. More specifically, heat sealing can be performed from a relatively low temperature, and even when the heat sealing temperature is set to be high, the heat sealing strength is not excessively increased and good easy-openability is ensured. Related to packaging materials.

[0002]

BACKGROUND OF THE INVENTION For packaging of foods and the like, a container made of polyethylene terephthalate, polyethylene naphthalate or polycarbonate is filled with an object to be packaged, and then a lid material is brought into contact with a filling port of the packaging container and heat sealed. A method is used. These forms of packaging are
Since it is necessary to peel off the lid material when removing the packaged object, there is no leakage of the packaged object between the container and the lid material, and the lid material can be easily peeled from the container when removing the packaged object. It is necessary to have a certain degree of heat sealing strength (easy opening property).

[0003] Such polyethylene terephthalate,
A saturated polyester resin is often used as the thermocompression-bonding adhesive for the easily-openable lid material used in containers made of polyethylene naphthalate or polycarbonate. However, when a polyester resin alone is used as the thermocompression bonding adhesive, the heat seal strength is often too high. Therefore, the heat seal strength of the polyester resin is generally reduced by adding another resin. Let it be used.

For example, Japanese Patent Publication No. 3-50704 discloses a lid material having a sealing layer in which a polyester resin is mixed with a polyethylene resin, and Japanese Patent Publication No. 3-50706 discloses a cover material having a sealing layer. A lid material having a sealing layer in which a resin having poor compatibility with the resin (specifically, a polyethylene resin) is blended with a resin is disclosed. Japanese Patent Application Laid-Open No. 63-87222 further discloses ,
An easily-openable film or the like made of a composition obtained by mixing a polyolefin-based resin with a polyester resin is disclosed.

In such a composition in which a polyolefin is blended with a polyester, the polyolefin is difficult to disperse in the polyester, and the adhesive strength may differ depending on the place where the polyolefin is bonded. Japanese Patent No. 2901324 discloses an easy-opening film composed of a polyester layer having a specific tensile elongation / adhesive polyolefin layer / polyolefin resin layer. The easy-opening film disclosed in this publication expresses the easy-opening property by exfoliating the polyester resin layer using the low elongation of the polyester resin. As disclosed in this publication, an easy-opening packaging material containing polyester as a main component is preferable in terms of fragrance retention and the like, but recently, the finish of the heat-sealed portion is more beautiful and can be molded at higher speed. In addition, a polyester-based easy-open packaging material that can be heat-sealed at a lower temperature is desired.

However, if a film having good heat sealability at a low temperature is to be used, the wound films are mutually blocked when forming the easily openable packaging material using the film. Such a film that has been strongly blocked has a problem that smooth unwinding of the film from the wound film may be difficult, and it may be difficult to manufacture a continuous packaging material.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a packaging material which is easily peelable from a polycarbonate or polyester container made of a thermoplastic resin such as polycarbonate, polyethylene terephthalate and polyethylene naphthalate.

Another object of the present invention is to provide an easy-open packaging material having a sealing surface with excellent block resistance. Another object of the present invention is to provide a packaging material capable of forming an appearance with less shrinkage of a sealed portion when heat-sealed.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an easy-open packaging material comprising at least two thermoplastic resin layers each having a base layer and a seal layer.
An easy-open packaging material characterized by having a peel strength of 1 N / 100 mm or less peeled at a speed between chucks of 200 mm / min after being left at 50 ° C. for 72 hours under a load of 25 kg on the area of .

The easy-opening packaging material of the present invention exhibits very good easy-opening properties, particularly for packaging materials made of polyester resin and packaging materials made of polycarbonate resin. When easily peelable packaging material of the present invention is peeled off by heat sealing to an adherend, delamination can be performed on the adherend while leaving a seal layer forming the easily openable packaging material on the adherend. preferable. That is, in the easy-open packaging material of the present invention, the heat-sealing strength between the seal layer and the adherend when heat-sealed is generally higher than the peel strength between the base layer and the seal layer.

The easily-openable packaging material of the present invention is preferably an easily-openable lid material. Furthermore, the easily openable packaging material of the present invention is such that the thermoplastic resin constituting the base layer laminated with the seal layer is composed of a modified polyolefin,
In addition, it is desirable that the thermoplastic resin constituting the seal layer is formed from a low-crystalline polyester composition.

The low-crystalline polyester composition for forming such a sealing layer is composed of a crystalline polyester A having a glass transition temperature of 40 ° C. or lower in 100 parts by weight of a resin component contained in the composition. Parts by weight and amorphous polyester B having a glass transition temperature of 70 ° C. or lower: 5 to 4
It is preferably contained in an amount of 0 parts by weight and having a melting point of 200 ° C. or less as a composition.

The sealing layer of the easily-openable packaging material according to the present invention comprises a crystalline polyester A and an amorphous polyester B, and the crystalline polyester A is a component unit acid derived from terephthal. And a dicarboxylic acid component unit having a component unit derived from an aliphatic dicarboxylic acid, and a repeating unit comprising a component unit derived from ethylene glycol and a diol component unit having a component unit derived from 1,4-butanediol. Preferably, the amorphous polyester B is a dicarboxylic acid component unit having a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid, and ethylene glycol. Component derived from cyclohexanedimethanol and component derived from cyclohexanedimethanol It is preferable that the polyester is composed of a repeating unit composed of a diol component unit having a position. The thickness of the surface layer formed of such a resin composition is preferably 10 μm or less.

In the easy-open packaging material of the present invention, the thermoplastic resin constituting the base layer is preferably formed of a modified polyolefin, and the modified polyolefin is partially or entirely unsaturated carboxylic acid or a derivative thereof. It is particularly preferred that the polyolefin is a modified polyolefin graft-modified. Furthermore, the easily openable packaging material of the present invention is:
The base layer may be two layers of the modified polyolefin layer and the unmodified polyolefin layer. The unmodified polyolefin is preferably polyethylene. or,
A uniaxial or biaxially stretched polyethylene terephthalate film and / or
Alternatively, it is preferable that a uniaxially or biaxially stretched polyamide film is further laminated.

Further, in the easy-open packaging material of the present invention, 0.1 to 3 parts by weight of the antistatic agent and / or 0.5 part by weight is used for 100 parts by weight of the resin component in the resin composition forming the seal layer. It is preferable that an anti-blocking agent is contained.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Next, the easily-openable packaging material of the present invention will be specifically described. As shown in FIG. 1, the easily-openable packaging material 1 of the present invention is a laminate of a base layer 10 and a seal layer 20. Although the base layer 10 may be a single layer, FIG. 1 shows an example in which the base layer 10 includes two layers, a layer 12 and a layer 15. Further, as shown in FIG. 2, the base layer 1 of the easy-open packaging material 1 on which the seal layer 20 is not formed.
It is preferable that the stretched film 22 is laminated on the surface of No. 0. In FIG. 2, the adhesive layer 16 is formed between the stretched film 22 and the base layer 10.

The layer 12 which is one layer of the base layer 10 forming the easy-open packaging material 1 of the present invention is formed of a film made of polyolefin. As the layer 12, for example, a film made of polyethylene such as high-pressure low-density polyethylene (so-called HP-LDPE), linear low-density polyethylene (so-called LLDPE), high-density polyethylene (so-called HDPE), or a polyolefin such as polypropylene and polybutene is used. be able to. For the base layer 12, it is preferable to use the above-mentioned resin excellent in water vapor barrier property, heat resistance and impact resistance. In particular, a polyolefin excellent in water vapor barrier property, heat resistance and impact resistance, particularly polyethylene and / or polypropylene, is used. It is preferred to use.

When polyethylene is used for the layer 12, the polyethylene to be used usually has a density of:
0.910 to 0.970 g / cm ³ , preferably 0.915
０．９0.935 g / cm ³ , measured by ASTM D1238D 19
HP-LDPE having a melt flow rate [MFR (190 ° C.)] at a load of 2.16 kg at 0 ° C. of usually 0.1 to 10 g / 10 min, preferably 0.5 to 5 g / 10 min is suitable.

When polypropylene is used for the layer 12, the polypropylene used is ASTM D
The melt flow rate [MFR (230 ° C)] at 230 ° C and a 2.16 kg load measured by 1238D is usually 0.1.
Polypropylene of from 20 to 10 g / 10 min, preferably from 0.51 to 10 g / 10 min is suitable. Further, layer 1 as described above
The resin forming 2 may be, for example, a mixture (composition) of the above-described polyolefins, or ethylene, propylene,
1-butene, 1-hexene, 1-octene and 4-methyl-1-
It may be a copolymer of α-olefins such as pentene.

The thickness of the substrate 12 is usually 5 μm or more, preferably 10 to 30 μm. By using the layer 12 having such a thickness, the obtained easily-openable packaging material has a strength enough to withstand practical use, and does not cause a significant increase in cost. In the easy-open packaging material of the present invention, the base layer 10 may be a single layer of the modified polyolefin, or may be formed from two layers of the polyolefin layer 12 and the modified polyolefin layer 15. Alternatively, the surface of the base layer 10 itself may be modified to impart adhesiveness. This modified polyolefin layer 15
Is a layer for ensuring an appropriate adhesiveness with the resin composition forming the seal layer 20. For example, when used as a lid material, the low crystalline polyester composition layer 20 and the container It does not peel off at the interface between the modified polyolefin layer 15 and the low-crystalline polyester composition layer 20 and does not peel off, and has excellent sealing properties for impurities, so that the contents may leak during storage or transportation. There is no.

In the present invention, in particular, it is preferable that the modified polyolefin layer 15 constituting one layer of the base layer 10 is partially or entirely formed of a modified polyolefin graft-modified with an unsaturated carboxylic acid or a derivative thereof. Examples of monomers for forming the raw polyolefin before modification used to form the modified polyolefin layer 15 include ethylene, propylene, 1-butene,
Olefins such as 1-hexene, 1-octene and 4-methyl-1-pentene can be mentioned. This olefin is used alone or in the form of a copolymer with another monomer to form a layer 15.
Constitute a modified polyolefin for forming Specific examples of the unmodified polymer obtained by (co) polymerizing such olefins include polyethylene, polypropylene, and polyolefin.
Α-olefins having 2 to 10 carbon atoms such as 1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, propylene / 1-butene copolymer be able to. Of these, polyethylene and ethylene / α-olefin copolymer are preferred in terms of film strength and the like. When an ethylene-α-olefin copolymer is used as the polymer before modification in the present invention, as the α-olefin to be copolymerized with ethylene, 1-butene, 1-hexene, 1-octene, 4-methyl- 1-
Penten is preferred.

In the ethylene / α-olefin copolymer, the repeating unit derived from ethylene is usually 80
The repeating unit derived from the α-olefin is usually more than 0 mol% and not more than 20 mol%, preferably 1 to 10 mol%. %. The melt flow rate [MFR (190 ° C)] of the ethylene / α-olefin copolymer before modification was measured at 190 ° C under a load of 2.16 kg according to ASTM D1238D, and is usually 20 to 0.001 g / 10.
Min, preferably in the range of 10 to 0.01 g / 10 min.

The method for producing such a (co) polymer before modification is not particularly limited. For example, it may be produced using a catalyst such as titanium (Ti), vanadium (V) or zirconium (Zr). Can be. By graft-modifying such an unmodified (co) polymer with an unsaturated carboxylic acid or a derivative thereof, a graft-modified polyolefin which is a resin suitable for forming the layer 15 can be produced.

Examples of the unsaturated carboxylic acids or derivatives thereof used herein include acrylic acid, methacrylic acid,
α-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, endocis- [2,2,1] hept-5
Unsaturated carboxylic acids such as -ene-2,3-dicarboxylic acid (Nadic acid _™ ) and derivatives thereof such as acid halides, amides, imides, acid anhydrides and esters. These can be used alone or in combination. Among these, maleic acid, nadic acid _TM or acid anhydrides thereof are particularly preferable.

The graft modification of the polyolefin can be carried out by a known method. For example, an unsaturated carboxylic acid or a derivative thereof and a radical initiator are added to a solution in which the polyolefin is dissolved in an organic solvent.
It can be denatured by reacting at a temperature of 50 ° C., preferably 80 to 190 ° C., usually for 0.5 to 15 hours, preferably 1 to 10 hours. The organic solvent that can be used in this reaction may be any organic solvent that can dissolve or disperse the unmodified polyolefin and the like and the modified polyolefin and the like, for example, benzene, toluene, aromatic hydrocarbon solvents such as xylene, pentane, hexene, Examples thereof include aliphatic hydrocarbon solvents such as heptane, and alicyclic hydrocarbon solvents. These solvents can be used alone or in combination.

As another graft modification method different from the above method, there is a method in which a modified product is prepared by contacting a polyolefin with an unsaturated carboxylic acid or a derivative thereof without using a solvent using an extruder or the like. . Regarding the reaction conditions in this case, the reaction temperature is usually 120 to 350 ° C., and the reaction time is usually 0.5 to 10 minutes. It is preferable to use a radical initiator in order to efficiently copolymerize the graft monomer and the unsaturated carboxylic acid or its derivative with the graph.

The radical initiator used for the graft modification in the present invention includes organic peroxides, organic peresters, azo compounds and the like. Examples thereof include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, and the like. Di-t-butyl peroxide, 2,5-dimethyl-2,5-di (peroxidebenzoate) hexine-3,2,5-bis (t-butylperoxyisopropyl) benzene, t-butylperbenzoate, t-
Examples thereof include butyl perphenyl acetate, t-butyl perisobutyrate, t-butyl per-sec-octoate, t-butyl ben diethyl acetate, and azobisisobutronitrile. These radical initiators can be used alone or in combination.
Among them, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t Preferred are dialkyl peroxides such as -butylperoxy) hexane and 1,4-bis (t-butylperoxyisopropyl) benzene. The radical initiator is an unmodified polyolefin 100
It is usually used in an amount of 0.001 to 1 part by weight based on part by weight.

The graft amount (graft modification rate) of the graft-modified product obtained by the graft modification in this manner is usually in the range of 0.05 to 10% by weight, preferably in the range of 0.05 to 5% by weight. However, the graft modification rate of the graft modified product that can be suitably used as the layer 15 in the present invention is usually 0.05 to 0.5% by weight, preferably 0.08 to 0.5% by weight.
% By weight. Therefore, in the present invention, a graft-modified product having a suitable graft-modification rate can be used alone or in combination, or an unmodified polymer can be added to a graft-modified product having a high graft-modification rate to the appropriate graft-modification rate as described above. It can also be used after adding and diluting it.

Such a layer 15 can be formed from the above-mentioned graft-modified product, and can be formed together with the graft-modified product or using another resin separately therefrom. Examples of such other resins include polyisoprene, ethylene / propylene rubber, ethylene / 1-butene rubber, 1-octene rubber, butyl rubber, butadiene rubber, styrene / butadiene rubber, ethylene / propylene rubber.
Butadiene rubber and isoprene rubber can be mentioned. Modified elastomers obtained by modifying these olefinic elastomers with the unsaturated carboxylic acids or derivatives thereof can also be used. These can be used alone or in combination. Among these, polyisobutylene, ethylene / propylene rubber, ethylene / 1-butene rubber, ethylene / 1-octene rubber and modified products thereof are preferably used. When the olefin-based elastomer is used together with the modified ethylene (co) polymer, any amount can be used without particular limitation as long as the properties of the layer 15 are ensured. It is usually at most 30 parts by weight, preferably at most 20 parts by weight, based on 100 parts by weight of the (co) polymer.

Such a substrate 10 may be composed of one layer of the modified polyolefin layer. However, since the modified polyolefin is generally more expensive than the unmodified polyolefin, it is laminated with the unmodified polyolefin layer 12. However, if at least two layers are used, the cost does not increase. When the base layer 10 has two layers, the base layer
May be co-extruded with a modified polyolefin to form a multilayer film, or may be formed by separately producing a film for forming the layer 15 and laminating the film on the layer 12. Alternatively, it can be produced by dissolving or dispersing a modified polyolefin as a forming component of the layer 15 in a solvent, applying the solution on the layer 12, and removing the solvent.

The easily peelable packaging material of the present invention can be produced by various production methods, for example, a thermoplastic resin such as a low-crystalline polyester forming the seal layer 20, a modified polyolefin forming the base layer, and a thermoplastic resin such as an unmodified polyolefin. A method in which the resin and the resin are each melted in separate extruders and co-extruded and molded using a multilayer die such as a two-layer or three-layer die, and a thermoplastic resin that forms a sealing layer on a pre-formed base film is laminated by extrusion And the like. When a low-crystalline polyester is used as the thermoplastic resin forming the seal layer, it is preferable to adopt a co-extrusion molding method.

In the present invention, the layer 15 can be preferably formed by using the above-mentioned modified ethylene (co) polymer, but separately from the unmodified polyolefin constituting the layer 12. The surface of the surface to be laminated with the seal layer 20 may be formed by, for example, a method of treating with an energy beam or a method of reacting a peroxide with the surface.

One preferred example of the easy-open packaging material of the present invention is a laminate of the base layer 10 on which the layer 15 is formed and the sealing layer 20. This seal layer 20 is preferably formed from a resin composition having a melting point of 200 ° C. or less. The film forming the seal layer 20 preferably has an elongation at break of 200% or more.

The film forming the seal layer 20 is usually formed from a low crystalline polyester composition. This low crystalline polyester composition, for example,
It consists of a polyester composition containing a crystalline polyester A and an amorphous polyester B. The melting point of the crystalline polyester A used in the present invention is usually 200 ° C. or lower, preferably in the range of 90 to 185 ° C., and the glass transition temperature (Tg) is usually 40 ° C. or lower, preferably −35 ° C.
It is a resin in the range of ２０20 ° C. When the melting point of the crystalline polyester A exceeds 200 ° C., the temperature of kneading with the amorphous polyester B may need to be set high, and the resin may be deteriorated by heating during kneading. Since the melting point of the composition with the crystalline polyester B also becomes high, there is a possibility that the film formation becomes difficult. Further, when such a resin is used, it is necessary to set the heat sealing temperature high, and there is a possibility that the openability of the obtained packaging material may be reduced. Polyester A used in the present invention has a melting point and is crystalline. When the glass transition temperature (Tg) of the crystalline polyester A exceeds 40 ° C., the heat sealability may be reduced in the present invention.

As another characteristic of the crystalline polyester A, the reduced viscosity measured for the crystalline polyester A is usually 0.5 to 2.5, preferably 0.6 to 2.0.
And the weight average molecular weight is usually 20,000 to 35
10,000, preferably in the range of 30,000 to 300,000. Examples of such a crystalline polyester A include a polyester obtained by polycondensation of a dicarboxylic acid and a diol. As the dicarboxylic acid used here, adipic acid, aliphatic dicarboxylic acids such as sebacic acid,
Examples include aromatic carboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and diphenylcarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. Examples of the diol include ethylene glycol, propylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol.

In order to adjust the characteristics of the crystalline polyester A as described above, an aliphatic dicarboxylic acid is used together with an aromatic dicarboxylic acid as a dicarboxylic acid component, and a relatively long carbon chain is used as a diol component. Polycondensation is carried out using a diol component. The crystalline polyester A having such properties is already commercially available, and is commercially available as the crystalline polyester A having the above properties, for example, under the trade name of “Vylon” (manufactured by Toyobo Co., Ltd.). Crystalline polyesters can be used.

Amorphous polyester B used in the present invention
Is based on polyethylene terephthalate, a dicarboxylic acid other than terephthalic acid may be used as a dicarboxylic acid component, and a diol component that increases the glass transition temperature of a polyester other than ethylene glycol as a diol component, preferably a diol component. It is a polyethylene terephthalate copolymer polycondensed using 1,4-cyclohexanedimethanol as a part. Examples of the dicarboxylic acid component other than the terephthalic acid component used herein include isophthalic acid, aromatic dicarboxylic acids such as diphenylene carboxylic acid, adipic acid, and aliphatic dicarboxylic acids such as sebacic acid. Examples of diol components other than ethylene glycol and 1,4-cyclohexanedimethanol include propylene glycol, 1,4-butanediol, and the like. Specific examples of such an amorphous polyester resin include polycondensates of ethylene glycol and terephthalic acid,
Condensation products of ethylene glycol, isophthalic acid and terephthalic acid, condensation polymers of 1,4-cyclohexanedimethanol, isophthalic acid and terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol, isophthalic acid and terephthalic acid And polycondensates of propylene glycol, isophthalic acid and terephthalic acid.

The weight average molecular weight of such an amorphous polyester B is usually in the range of 10,000 to 400,000, and the glass transition temperature (Tg) is usually higher than 40 ° C., preferably 4 ° C.
It is in the range of 5-90C. Since this amorphous polyester B does not have crystallinity, it does not crystallize in the heating and cooling step when used alone. Particularly, in the present invention, as the amorphous polyester B, a copolyester resin in which at least a part of the component units derived from ethylene glycol forming polyethylene terephthalate is replaced by component units derived from 1,4-cyclohexanemethanol is used. Is preferred.

Such an amorphous copolyester-based resin is already commercially available. In the present invention, as an amorphous polyester B having the above-mentioned properties, for example, “PE”
An amorphous copolyester resin commercially available under the trade name of "TG" (manufactured by Eastman Kodak Company) can be used. In the present invention, the above-mentioned crystalline polyester A
And an amorphous polyester B are preferably used. That is, the crystalline polyester A
And the amorphous polyester B are melt-kneaded to form a heat-sealing composition, and a heat-sealing layer is formed on the surface of the base material using the heat-sealing composition. The heat-sealable composition uses the crystalline polyester A in an amount within a range of, for example, 60 to 95 parts by weight, and preferably 70 to 90 parts by weight, and uses the amorphous polyester B in, for example, 5 to 4 parts by weight.
It is used in an amount of 0 parts by weight, preferably in the range of 10 to 30 parts by weight. The low-crystalline polyester composition composed of the crystalline polyester A and the amorphous polyester B in the above-described compounding ratio is particularly excellent in low-temperature heat-sealing property with a polyester sheet or polycarbonate, and peels off the sealed portion 40. In this case, for example, as shown in FIG. 3, the delamination occurs, so that it has a characteristic that the foreign matter sealing property is excellent.

Sealing layer 2 of easy-open packaging material 1 of the present invention
The low-crystalline polyester resin composition, which is a preferred example of the thermoplastic resin forming 0, has a melting point of usually 20.
0 ° C. or lower, preferably 180 ° C. or lower, particularly preferably 7 ° C.
It is in the range of 0 ° C to 180 ° C. By using a low crystalline polyester having such a melting point, good heat seal strength is exhibited at a low temperature, and the heat seal strength does not significantly increase even when the heat seal temperature is increased.

Seal layer 2 of easy-open packaging material 1 of the present invention
Various compounding agents usually added to the thermoplastic resin forming 0, for example, heat stabilizers, slip agents, antistatic agents, antiblocking agents, ultraviolet absorbers, weather stabilizers, light stabilizers, antifogging agents In addition, additives such as a nucleating agent, a lubricant, a dye that absorbs only light of a specific wavelength, a pigment, a natural oil, a synthetic oil, a wax or a light-transmissive filler can be blended.

In particular, the easy-open packaging material of the present invention supplies a raw film supplied in a wound state to a processing device and processes it into a predetermined form. For stable supply, it is preferable to mix an antistatic agent, an antiblocking agent and a slip agent with the thermoplastic resin forming the seal layer. Such additives are usually incorporated in the thermoplastic resin in an amount of 10% by weight or less, preferably 7% by weight or less, particularly preferably 0.6 to 7% by weight. In particular, when silica is used as an antiblocking agent, its addition amount is usually 0.5 to 5% by weight based on the total resin amount, and the addition amount of the antistatic agent is usually 0.1 to 3%. % By weight.

In particular, the thermoplastic resin forming the seal layer used in the present invention preferably contains an antiblocking agent and an antistatic agent. Examples of the anti-blocking agent used herein include silica powder, calcium carbonate, calcium silicate and aluminum silicate, and examples of the antistatic agent include
Glycerin higher fatty acid mono- or diesters, and
Diglycerin higher fatty acid mono- or diesters can be mentioned.

Examples of slip agents which may be used in the present invention include higher fatty acid amides such as erucamide and oleic acid, and higher fatty acids such as ethylenebisoleic acid amide and ethylenebiserucamide. Bisamide and the like can be mentioned. The seal layer 20 formed of the thermoplastic resin having the above components has a thickness of usually 10 μm or less, preferably 3 to 8 μm.

The seal layer 20 of the easily-openable packaging material 1 of the present invention is preferably formed from the low-crystalline polyester composition as described above. When you measure elongation,
The elongation at break (elongation at break) of this film is usually 200
% Or more, preferably 350% or more, particularly preferably 35% or more.
It is in the range of 0% to 450%. When a film made of the low-crystalline polyester composition in which the specific crystalline polyester A and the amorphous polyester B described in the present invention are mixed at a specific ratio is used, the sealing layer 20 has such a high elongation at break. Despite that, when the easy-open packaging material of the present invention is used as a lid material for a container, strong heat sealing that causes delamination without fear of leakage of contents during transportation or the like is possible, and It has a characteristic that when an object is taken out, it can be easily peeled off by delamination.

Then, the easily-openable packaging material 1 of the present invention comprises:
It has excellent blocking resistance, and after winding and holding the film, the film forming the easily openable material 1 to be unwound is easily peeled off from the wound film, and a large force is required for unwinding the film. There is an excellent property that it is not required. The blocking resistance is quantitatively confirmed by closely adhering the sealing layer 20 that is most likely to cause blocking, adjusting the sample for measuring the blocking resistance, and determining the peel strength between the sealing layers 20 and 20. be able to.

That is, a test piece was cut out from the easily-openable packaging material of the present invention, and two test pieces were stacked so that the sealing layer 20 faced, and a load of 25 kg was applied to an area of 100 mm × 100 mm of the test piece. And left at 50 ° C. for 72 hours. Next, when the peel strength of the test piece is measured using a peel strength measuring device in which the speed between chucks is set to 200 mm / min, the peel strength of the easily-openable packaging material of the present invention is 1 N / 100 mm or less, preferably Is 0.1-0.5N / 100mm
Shows a very low value in the range. Therefore, the easily-openable packaging material of the present invention is less likely to cause blocking in the film wound and stored after the production, and the step of laminating with the layer 22 of a stretched polyester resin or a stretched polyamide resin using the easily-openable packaging material. Therefore, troubles such as rewinding are less likely to occur, and a good film can be manufactured.

As described above, the easily-openable packaging material of the present invention comprises the base layer 10 (which may be composed of one layer of a modified polyolefin layer and two layers of an unmodified polyolefin layer). The sealing material 20 according to the present invention is further provided with a layer 2 on the surface where the seal layer 20 is not formed, as shown in FIG.
2 may be arranged. By forming the layer 22 and selecting various materials for forming the layer, characteristics such as mechanical strength, heat resistance, and cold resistance can be improved.

The layer 22 can be formed of paper, non-woven fabric, resin film, metal foil, metal vapor-deposited foil, etc., which has been conventionally used as a packaging material. Can be used. In the present invention, it is particularly preferable to use a resin film as the layer 22. Examples of the resin film forming this layer include a uniaxial or biaxially stretched polyamide film (eg, nylon 6, nylon 66, etc.), a uniaxial or Examples include a biaxially stretched polyester film (eg, a polyethylene terephthalate film).

This layer 22 is usually laminated on the base layer 10 via the adhesive layer 16. The adhesive layer 16 can be formed with an adhesive having the same adhesiveness as the base layer 10 or the layer 15. In addition, when laminating the low-crystalline polyester composition / modified polyolefin / unmodified polyolefin, for example, this layer 22 can be formed using a method such as dry lamination, extrusion lamination, or sandwich lamination. it can.

When the easily-openable packaging material 1 of the present invention has the layer 22 as described above, the thickness of the layer 22 can be appropriately set, but is usually 12 to 500 μm, preferably 12 to 50 μm. It is. When the layer 22 is laminated on the easy-open packaging material with the adhesive layer 16 interposed therebetween, the thickness of the adhesive layer 16 is usually 3 to 20 μm, preferably 3 to 10 μm.

The easy-open packaging material 1 of the present invention can be prepared by a conventional laminating method, for example, a co-extrusion laminating method, an extrusion coating method,
It can be manufactured by employing various laminating methods such as a thermal laminating method. The easy-open packaging material of the present invention can be particularly suitably used, for example, as an easy-open lid material. In addition, the easy-opening packaging material using the heat-sealable composition containing the polyolefin resin (composition for forming a surface film) has good heat-sealability with respect to polyethylene terephthalate, polyethylene naphthalate, and polycarbonate base materials. In addition, it shows excellent easy-openability especially when heat-sealed with these substrates. However, good easy-opening properties can be exhibited by adjusting the heat-sealing conditions also for the adherend formed from another resin.

The easily-openable packaging material of the present invention can be placed in such a manner that the sealing layers face each other and heat-sealed to form a bag-like package, or it can be used as a lid for a container. it can. Fig. 3 shows a sheet (other material) that becomes a container
It is a figure which shows the state which peeled off after the lid body which consists of the easy-open packaging material 1 of this invention was heat-sealed to the upper surface edge part of 30. In FIG. 3, reference numeral 40 represents a heat seal portion.

The easily-openable packaging material of the present invention preferably has the structure shown in FIG. 2, in which a sealing layer 20 made of a low-crystalline polyester composition is heat-sealed to the edge of the upper surface of the container. . When the lid is peeled off, the lid can be easily peeled off by delamination between the modified polyolefin layer 15 constituting the base layer 10 and the seal layer 20.

[0055]

The easily-openable packaging material of the present invention is less likely to cause blocking in the film wound and stored after production, and the easily-openable packaging material is used to form a layer 22 such as a stretched polyester resin or a stretched polyamide resin. In the laminating step, troubles such as rewinding are less likely to occur, and a good film can be produced. Further, by using a thermoplastic resin consisting of a specific low crystalline polyester composition containing a crystalline polyester resin and an amorphous polyester resin as a seal layer, using a modified polyolefin layer as a base layer, relatively low Heat seal strength sufficient to express easy peelability from temperature is obtained,
Even when the heat sealing temperature is increased, the low-crystalline polyester composition layer and the modified polyolefin layer are separated, so that the easy-opening property can be maintained and the heat sealing strength does not become extremely high.

Further, according to the present invention, it has good heat heel properties with respect to polyesters such as polyethylene terephthalate and polyethylene naphthalate and polycarbonates, and also has good heat heel properties when heat sealed with containers made of these resins. Easy openability and heat seal strength can be achieved. Furthermore, when the low-crystalline polyester composition is used as the sealing layer, the composition is located in the innermost layer, so that it is excellent in fragrance retention.

[0057]

EXAMPLES The following is a description of the easily openable packaging material of the present invention with specific examples, but the present invention is not limited thereto.

[0058]

Example 1 Crystalline polyester A having a melting point of 12
3 ° C., a glass transition temperature (Tg) of −70 ° C., a weight average molecular weight of 30,000 to 40,000, and a density of 1.2.
6 g / cm ³ crystalline polyester (trade name: Byron _™ GM)
913, manufactured by Toyobo Co., Ltd.).

Separately, as amorphous polyester B, the glass transition temperature (Tg) is 81 ° C. and the weight average molecular weight is 2
Amorphous polyester having an intrinsic viscosity of 0.75 and a density of 1.27 g / cm ³ (trade name: PET-G _™ 6763,
Eastman Kodak). 90 parts by weight of the crystalline polyester A, 10 parts by weight of the amorphous polyester B, and 100 parts by weight of these resins in total, an antistatic agent (trade name: Chemistat _™ PEG6000, manufactured by Sanyo Chemical Industries, Ltd.) 0.4 A low-crystalline polyester composition (resin composition forming a heat layer) is prepared by melt-kneading 0.5 parts by weight of a silica powder having an average particle diameter of 3.0 μm as an anti-blocking agent by weight. did.

The amorphous polyester B was prepared by adding a part of ethylene glycol of polyethylene terephthalate produced from terephthalic acid and ethylene glycol to 1,2.
Polyethylene terephthalate in place of 4-cyclohexanedimethanol. As the base layer, high-pressure low-density polyethylene (trade name: Mirason _™ M12P, Mitsui Chemicals, Inc.)
, MFR: 3 g / 10 min, density: 0.927 g / cm ³ ).

As a modified polyolefin forming a layer to be laminated with the seal layer as a base layer, a polyethylene / 1-octene random copolymer (A) (MFR (190 ° C.): 4 g / 10 min, density: 0.920 g / cm) ³ ), ethylene / propylene random copolymer (B) (ethylene content: 70 mol%, density: 0.1%)
870 g / cm ³ ), maleic anhydride graft-modified polyethylene (C) (maleic anhydride content: 1% by weight, density: 0.1%).
960 g / cm ³ ) with (A) / (B) / (C) = 65/5
After melt-kneading at a ratio of / 30% by weight with a Henschel mixer, the mixture was granulated to prepare a modified polyolefin.

The above three components were co-extruded in three layers to form a three-layer film as an easily-openable packaging material. The co-extrusion conditions at this time were such that the low-crystalline polyester composition serving as the seal layer, the modified polyolefin as one of the base layers, and the high-pressure low-density polyethylene as the other base layer were simultaneously formed by 230.
The conditions were set so that coextrusion was possible at an extrusion temperature of ° C. The thickness of each layer of the obtained three-layer film composed of the seal layer / base layer (modified polyolefin layer) / base layer (unmodified polyolefin layer) was 5 μm / 10 μm / 15 μm.

Next, the high-pressure low-density polyethylene (back side) of the obtained co-extruded three-layer film and a biaxially stretched polyamide film (ONy) having a thickness of 15 μm were laminated by dry lamination using a urethane-based adhesive. Thus, a lid material as the easily-openable packaging material of the present invention was produced. [Evaluation Methods] In the examples of the present invention, various evaluations were performed by the following methods. 1) Heat seal strength An amorphous polyester resin sheet (trade name: Orphan PET sheet) having a thickness of 220 μm on the seal layer (low crystalline polyester layer) of the easy-opening film produced by the above method.
(Made by Osaka Resin Chemical Co., Ltd.) and heat sealed under the following conditions.

Seal bar temperature: described in Table 1 Pressure: 0.2 MPa Seal bar width: 5 mm Sealing time: 1 second Next, the test piece obtained by the above method was pulled at a tensile speed of 5 using a universal testing machine.
Perform a T-peel test at 00 mm / min and average strength (N / 15m
m) was taken as the heat seal strength. 2) Contaminant Sealability A three-sided heat-sealed bag product of 100 mm × 200 mm was manufactured using the easily openable packaging material. Kimchi pickles containing water were put through the opening, and the bag was closed by fusing by heat sealing. The state of the seal and the liquid leakage were evaluated. 3) Blocking strength (peeling strength) This was performed by a method according to ASTM-D1893. That is, 150 × 10
25mm to 100mm x 100mm area for 0mm rectangular sample
A load of kg was placed and left in an air oven at 50 ° C. for 3 days (72 hours). The blocking strength was determined as the strength (peel strength) (N) when this sample was peeled at a speed of 200 mm / min.
/ 100mm). 4) Elongation at Break of Low-Crystalline Polyester Composition Film A cast film having a thickness of 50 μm made of the polyester composition having the composition described in Examples and Comparative Examples was prepared, and a tensile test piece was cut out from this film and subjected to ASTM-D882. The elongation at break was determined by performing a tensile test in accordance with the above method.
The tensile test was performed at a tensile speed of 300 mm / min.

Table 1 shows the results.

[0066]

Examples 2 to 5 In Example 1, the compounding amounts of the crystalline polyester A, Byron _™ , the amorphous polyester B, PET-G _™ , and the compounding amounts of the antistatic agent and the fine powdered silica were shown. An easy-open packaging material was produced in the same manner except that the composition was changed as shown in FIG.

The properties of the obtained easy-open packaging material were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[0068]

Comparative Examples 1 to 6 In Example 1, the compounding amounts of the crystalline polyester A, Byron _™ , the amorphous polyester B, PET-G _™ , and the compounding amounts of the antistatic agent and the fine silica powder were shown. An easy-open packaging material was produced in the same manner except that the composition was changed as shown in FIG.

The properties of the obtained easy-open packaging material were evaluated in the same manner as in Example 1. The results are also shown in Table 1.

[0070]

[Table 1]

As is clear from Table 1, the packaging material satisfying the requirements of the present invention has a blocking strength of 1 N / 100 m.
m or less, and is excellent in workability and laminating characteristics during film production and cutting. Further, the packaging material satisfying the requirements of the present invention, as shown in FIG.
It has excellent sealability for impurities and shows good openability when taking out the contents. On the other hand, as shown in FIG. 4, the packaging materials of Comparative Examples 1 to 5 are heat-sealed to another material 30, and when the heat-sealed portion 40 is peeled off, interfacial peeling is caused, and the impurity sealing property is poor. Further, the packaging materials satisfying the requirements of the present invention have little change in heat sealing strength when heat-sealed at 125 ° C. and at 130 ° C., whereas the packaging materials of Comparative Examples 1 to 5 are heat-sealed. Heat seal strength varies greatly with temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating an example of the configuration of an easily-openable packaging material of the present invention.

FIG. 2 is a cross-sectional view schematically showing another example of the configuration of the easily-openable packaging material of the present invention.

FIG. 3 is a cross-sectional view schematically showing an example in which the heat-sealing portion is peeled off after heat-sealing with another material using the easily-opening packaging material of the present invention.

FIG. 4 is a cross-sectional view schematically illustrating an example in which the heat-sealing portion is peeled off after heat-sealing with another material using the easily-opening packaging material shown in the comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Easy-open packaging material 10 ... Base layer 12 ... Base layer (unmodified polyolefin layer) 15 ... Base layer (modified polyolefin layer) 16 ... Adhesive layer 20 ... Seal layer 22. ..Backside layer 30 ... Other materials 40 ... Heat seal part

Continued on the front page F term (reference) 3E086 AD23 BA04 BA15 BA33 BB51 BB85 BB90 CA01 4F100 AA20H AK01A AK01B AK01C AK01D AK03A AK03D AK06 AK24A AK24 AL AK41B AK41C AK42 AK45B04 AK45BAK AK45B BA06 BA07 BA10B BA10C CA22 EH20 EH202 EJ37B EJ37C GB15 GB18 JA05B JA05C JA11B JA11C JA12B JA12C JB16A JB16B JB16C JB16D JK06B JK06C JL11B JL11C JL14 YY00B YY00C 4J002 CF031 CF032 CF051 CF052 GF00 GG02 4J029 AA03 AB01 AB07 AC02 AD07 AD10 AE03 BA03 BA05 BA08 BD07A CA02 CA06 CB04A CB05A CB06A CB10A CD03

Claims (12)

[Claims] 1. An easy-open packaging material comprising at least two thermoplastic resin layers each having a base layer and a seal layer,
The seal layers are overlapped to form an area of 100 mm x 100 mm.
After leaving at a temperature of 50 ° C. for 72 hours under a load of 5 kg, the peel strength peeled off at a speed of 200 mm / min between the chucks is 1
An easily openable packaging material having a size of N / 100 mm or less. 2. The easy-open packaging material according to claim 1, wherein said easy-open packaging material is delaminated while leaving a seal layer on the heat-sealed adherend. 3. The easy-open packaging material according to claim 1, wherein the thermoplastic resin constituting the seal layer is formed from a low-crystalline polyester composition. 4. The low-crystalline polyester composition forming the seal layer is composed of 60 to 95 parts by weight of a crystalline polyester A having a glass transition temperature of 40 ° C. or less, and a glass transition temperature of 7
The easy-open packaging material according to claim 3, wherein the composition is a composition comprising 5 to 40 parts by weight of an amorphous polyester B having a temperature of 0 ° C or less. 5. A dicarboxylic acid unit, wherein the crystalline polyester A has a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid,
Component units derived from ethylene glycol and 1,4-
The easy-open packaging material according to claim 4, which is a polyester comprising a repeating unit composed of a diol component unit having a component unit derived from butanediol. 6. The above-mentioned amorphous polyester B comprises a dicarboxylic acid component unit having a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid, a component unit derived from ethylene glycol, and cyclohexane. 5. A polyester comprising a repeating unit consisting of a diol component unit having a component unit derived from dimethanol.
Item. 7. The easy-open packaging material according to claim 3, wherein the thickness of the surface layer comprising the low-crystalline polyester composition is 10 μm or less. 8. The easy-open packaging material according to claim 1, wherein the thermoplastic resin constituting the base layer is formed from a modified polyolefin. 9. The easy-open package according to claim 1, wherein the base layer comprises at least two layers of an unmodified polyolefin and a modified polyolefin, and the modified polyolefin layer is in contact with the sealing layer. Packaging material. 10. The easy-open property according to claim 8, wherein the modified polyolefin is a modified polyolefin partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof. Packaging material. 11. A modified polyolefin layer forming a base layer, or a polyolefin layer and a modified polyolefin layer,
The easy-open packaging material according to claim 8, wherein a stretched polyethylene terephthalate film and / or a stretched polyamide film are laminated on a surface of the base layer on which the seal layer is not laminated. 12. The container according to claim 1, wherein the easy-open packaging material is a container made of a polyester-based resin or a lid material of a container made of a polycarbonate-based resin. An easily openable packaging material according to any one of the above items.