JP4601768B2 - Easy-open packaging material - Google Patents

Description

【００７１】
上記表１から明らかなように、本発明の要件を満たす包装材料は、ブロッキング強度が１Ｎ／100mm以下であり、フィルムの製造時、裁断時の加工性およびラミネート加工特性に良好である。また、本発明の要件を満たす包装材料は、図３に示すように、ートシールした後剥離する際にヒートシール部４０で層間剥離し、夾雑物シール性に優れ、しかも内容物を取出す際には良好な易開封性を示す。
それに対して比較例１〜５の包装材料は、図４に示すように、他材料３０にヒートシールし、このヒートシール部４０を剥離した場合に界面剥離を起こし、夾雑物シール性に劣る。さらに、本発明の要件を満たす包装材料は１２５℃でヒートシールしたときと、１３０℃でヒートシールしたときのヒートシール強度の変動が少ないのに対して比較例１〜５の包装材料はヒートシール温度によるヒートシール強度の変動が大きい。
【図面の簡単な説明】
【図１】図１は、本発明の易開封性包装材料の構成の例を模式的に示す断面図である。
【図２】図２は、本発明の易開封性包装材料の他の構成の例を模式的に示す断面図である。
【図３】図３は、本発明の易開封性包装材料を用いて他材料とヒートシールした後、ヒートシール部を剥離した例を模式的に示す断面図である。
【図４】図４は、比較例に示す易開封性包装材料を用いて他材料とヒートシールした後、ヒートシール部を剥離した例を模式的に示す断面図である。
【符号の説明】
１・・・易開封性包装材料
１０・・・基層
１２・・・基層（未変性ポリオレフィン層）
１５・・・基層（変性ポリオレフィン層）
１６・・・接着剤層
２０・・・シール層
２２・・・裏面層
３０・・・他材料
４０・・・ヒートシール部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an easily openable (easy peel) packaging material. More specifically, it is possible to heat-seal from a relatively low temperature, and even when the heat-sealing temperature is set high, the heat-sealing strength is not excessively increased and good easy-openability is ensured. It relates to packaging materials that can
[0002]
TECHNICAL BACKGROUND OF THE INVENTION
For packaging of foods, etc., a method is used in which a package made of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, or the like is filled with an object to be packaged, and then the lid is brought into contact with the filling port of the packaging container and heat sealed. . In such a form of the package, it is necessary to peel off the cover material when taking out the package, so there is no leakage of the package between the container and the cover material, and from the container when taking out the package. It is necessary to have a heat seal strength that allows the lid material to be easily peeled off (easy opening).
[0003]
Saturated polyester resins are often used as thermocompression adhesives for easy-opening lid materials used in containers made of polyethylene terephthalate, polyethylene naphthalate, or polycarbonate. However, if a polyester resin alone is used as a thermocompression adhesive, the heat seal strength is often too high, so generally the heat seal strength of a polyester resin is reduced by blending with other resins. Have been used.
[0004]
For example, Japanese Patent Publication No. 3-50704 discloses a cover material having a sealing layer in which a polyethylene resin is blended with a polyester resin, and Japanese Patent Publication No. 3-50706 discloses a polyester resin. Further, there is disclosed a lid member having a sealing layer containing a resin (specifically, a polyethylene resin) having a poor compatibility with the resin. Further, Japanese Patent Laid-Open No. 63-87222 discloses a polyester resin. An easy-open film made of a composition in which a polyolefin resin is mixed is disclosed.
[0005]
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-open film comprising a polyester layer / adhesive polyolefin layer / polyolefin resin layer having a specific tensile elongation. The easy-open film disclosed in this publication exhibits easy-openability by delamination of the polyester resin layer using the low elongation rate of the polyester resin. As disclosed in this publication, an easy-open packaging material containing polyester as a main component is preferable in terms of aroma retention, etc., but recently the heat-sealed part has a cleaner finish and can be molded at a higher speed. In addition, polyester-based easy-open packaging materials that can be heat-sealed at lower temperatures are desired.
[0006]
However, if an attempt is made to use a film having good heat sealability at low temperatures, the films wound when forming an easy-open packaging material using this film will block each other. Such a firmly blocked film may make it difficult to smoothly unwind the film from the wound film, which makes it difficult to produce a continuous packaging material.
[0007]
OBJECT OF THE INVENTION
It is an object of the present invention to provide a packaging material that is easily peelable from a polycarbonate container or a polyester container made of a thermoplastic resin such as polycarbonate, polyethylene terephthalate, or polyethylene naphthalate.
[0008]
Furthermore, an object of the present invention is to provide an easy-open packaging material having a sealing surface excellent in block resistance.
Another object of the present invention is to provide a packaging material capable of forming an appearance with less shrinkage of the seal portion when heat-sealed.
[0009]
Summary of the Invention
The present invention is an easy-open packaging material comprising at least two thermoplastic resin layers having a base layer and a seal layer,The sealing layer is
  Dicarboxylic acid unit having a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid, and a diol having a component unit derived from ethylene glycol and a component unit derived from 1,4-butanediol Polyester composed of repeating units consisting of component unitsCrystalline polyester A having a glass transition temperature of 40 ° C. or lower:70 to 90 parts by weightWhen,
Dicarboxylic acid component unit having a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid, and a diol component unit having a component unit derived from ethylene glycol and a component unit derived from cyclohexanedimethanol The glass transition temperature which is a polyester composed of repeating units consisting ofAmorphous polyester B:A sealing layer containing 10 to 30 parts by weight;
  The seal layer is peeled off while leaving the seal layer on the heat-sealed adherend, and the seal layers are overlapped with each other and left to stand at 50 ° C. for 72 hours with a load of 25 kg on an area of 100 mm × 100 mm. The peel strength peeled at a speed of 200 mm / min is 1 N / 100 mm or less,
  The adherend is a container made of a polyester resin or a container made of a polycarbonate resin.Easy-open packaging materialAbout.
[0010]
  The easy-open packaging material of the present invention exhibits a very good easy-open property especially for a packaging material made of a polyester-based resin and a packaging material made of a polycarbonate-based resin. When the easy-open packaging material of the present invention is heat-sealed to an adherend and peeled off, the seal layer for forming the easy-open packaging material on the adherend is left on the adherend and peeled off.Is.That is, in the easy-open packaging material of the present invention, the heat seal strength between the seal layer and the adherend when heat-sealed is usually higher than the peel strength between the base layer and the seal layer.
[0011]
Moreover, it is preferable that the easy-open packaging material of this invention is an easy-open lid material.
Further, in the easy-open packaging material of the present invention, the thermoplastic resin constituting the base layer laminated with the seal layer is made of a modified polyolefin, and the thermoplastic resin constituting the seal layer is formed from a low crystalline polyester composition. It is desirable that
[0012]
  And the low crystalline polyester composition which forms such a sealing layer is crystalline polyester A having a glass transition temperature of 40 ° C. or less in 100 parts by weight of the resin component contained in the composition:70 to 90 parts by weightAnd the glass transition temperature is45 ° C-90 ° CAmorphous polyester B:10-30 parts by weightIt is preferable that the melting point of the composition is 200 ° C. or less.
[0013]
  Further, the seal layer of the easy-open packaging material of the present invention contains crystalline polyester A and amorphous polyester B, and the crystalline polyester A is a component unit acid derived from terephthal and an aliphatic group. It is composed of a repeating unit consisting of a dicarboxylic acid component unit having a component unit derived from dicarboxylic acid, a component unit derived from ethylene glycol, and a diol component unit having a component unit derived from 1,4-butanediol. PolyesterYes,Amorphous polyester B is derived from 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 cyclohexanedimethanol. Comprising a repeating unit comprising a diol component unit having a component unitIt is.The thickness of the surface layer formed of such a resin composition is preferably 10 μm or less.
[0014]
In the easy-open packaging material of the present invention, the thermoplastic resin constituting the base layer is preferably formed from a modified polyolefin, but this modified polyolefin is partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof. Particularly preferred is a modified polyolefin.
Further, in the easy-open packaging material of the present invention, the base layer may be two layers of the modified polyolefin layer and the unmodified polyolefin layer. Such unmodified polyolefin is preferably polyethylene. Moreover, it is preferable that a uniaxial or biaxially stretched polyethylene terephthalate film and / or a uniaxial or biaxially stretched polyamide film is further laminated on the surface of the base layer on which the seal layer is not laminated.
[0015]
Further, in the easy-open packaging material of the present invention, 0.1 to 3 parts by weight of an antistatic agent and / or 0.5 part by weight of an antistatic agent is used per 100 parts by weight of the resin component in the resin composition forming the seal layer. It is preferable that a blocking agent is contained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, the easy-open packaging material of the present invention will be specifically described.
As shown in FIG. 1, the easy-open 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 of a layer 12 and a layer 15. Moreover, as shown in FIG. 2, it is preferable that the stretched film 22 is laminated | stacked on the surface of the base layer 10 in which the sealing layer 20 of this easy-open packaging material 1 is not formed. In FIG. 2, the adhesive layer 16 is formed between the stretched film 22 and the base layer 10.
[0017]
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 from 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 polyolefin such as polypropylene and polybutene is used. be able to. The base layer 12 is preferably made of the above-described resin having excellent water vapor barrier properties, heat resistance, and impact resistance. Particularly, polyolefin, particularly polyethylene and / or polypropylene, excellent in water vapor barrier properties, heat resistance, and impact resistance is used. It is preferable to use it.
[0018]
When polyethylene is used for this layer 12, the polyethylene used is usually from 0.910 to 0.970 g / cm in density.^Three, Preferably 0.915 to 0.935 g / cm^ThreeThe melt flow rate [MFR (190 ° C)] at 2.16 kg load at 190 ° C. measured by ASTM D1238D is usually 0.1 to 10 g / 10 min, preferably 0.5 to 5 g / 10 min. Is preferred.
[0019]
When polypropylene is used as the layer 12, the polypropylene used has a melt flow rate [MFR (230 ° C)] at a load of 2.16 kg at 230 ° C measured by ASTM D1238D of usually 0.1 to 20 g / 10 min. Polypropylene, preferably from 0.51 to 10 g / 10 min is suitable.
Further, the resin forming the layer 12 as described above may be, for example, a mixture (composition) of the polyolefin as described above, and ethylene, propylene, 1-butene, It may be a copolymer of α-olefins such as 1-hexene, 1-octene and 4-methyl-1-pentene.
[0020]
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 easily openable packaging material obtained has a strength that can withstand practical use, and does not incur a significant cost increase.
In the easy-open packaging material of the present invention, the base layer 10 may be a single modified polyolefin layer, or may be formed of two layers, the polyolefin layer 12 and the modified polyolefin layer 15. Further, the surface of the base layer 10 itself may be modified to impart adhesiveness. The modified polyolefin layer 15 is a layer for ensuring appropriate adhesiveness with the resin composition forming the seal layer 20. For example, when used as a lid, the low crystalline polyester composition described above at the time of opening. It does not peel at the interface between the layer 20 and the container 2 but has a property of peeling between the modified polyolefin layer 15 and the low crystalline polyester composition layer 20, and has excellent contaminant sealing properties, so that the contents are stored. Alternatively, there is no risk of leakage during transportation.
[0021]
In particular, in the present invention, the modified polyolefin layer 15 constituting one layer of the base layer 10 is preferably formed of a modified polyolefin partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof.
Examples of monomers for forming the raw polyolefin before modification used for forming the modified polyolefin layer 15 include ethylene, propylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene. And olefins. These olefins constitute a modified polyolefin for forming the layer 15 alone or copolymerized with other monomers. Specific examples of such a polymer before (co) polymerization of olefins include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymer, and ethylene / 1-butene copolymer. Examples thereof include α-olefins having 2 to 10 carbon atoms such as polymers and propylene / 1-butene copolymers. Among these, polyethylene and ethylene / α-olefin copolymers are preferable 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, the α-olefin copolymerized with ethylene includes 1-butene, 1-hexene, 1-octene, 4-methyl- 1-pentene is preferred.
[0022]
In the ethylene / α-olefin copolymer, the repeating unit derived from ethylene is usually in the range of 80 mol% or more and less than 100 mol%, preferably 90 to 99 mol%, and derived from the α-olefin. The repeating unit is usually in the range of more than 0 mol% and 20 mol% or less, preferably 1 to 10 mol%. The melt flow rate [MFR (190 ° C.)] measured at 190 ° C. under a load of 2.16 kg according to ASTM D1238D for the ethylene / α-olefin copolymer before modification is usually 20 to 0.001 g / 10 min, preferably It is in the range of 10 to 0.01 g / 10 minutes.
[0023]
The method for producing such a (co) polymer before modification is not particularly limited, and for example, it can be produced using a catalyst of titanium (Ti), vanadium (V), zirconium (Zr) or the like.
By graft-modifying such an unmodified (co) polymer with an unsaturated carboxylic acid or a derivative thereof, a graft-modified polyolefin that is a resin suitable for forming the layer 15 can be produced.
[0024]
Examples of unsaturated carboxylic acids or derivatives thereof used here 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-ene-2,3-dicarboxylic acid (nadic acid)_TM) And derivatives thereof such as acid halides, amides, imides, acid anhydrides and esters thereof. These can be used alone or in combination. Of these, maleic acid and nadic acid_TMOr these acid anhydrides are suitable.
[0025]
The graft modification of polyolefin can be performed by a known method. For example, an unsaturated carboxylic acid or a derivative thereof and a radical initiator are added to a solution obtained by dissolving the polyolefin in an organic solvent, and the temperature is usually 60 to 350 ° C., preferably 80 to 190 ° C., usually 0.5 to It can be modified by reacting for 15 hours, preferably 1 to 10 hours. The organic solvent that can be used in this reaction may be an organic solvent that can dissolve or disperse the unmodified polyolefin and the modified polyolefin. For example, aromatic solvents such as benzene, toluene, and xylene, pentane, hexene, Examples include aliphatic hydrocarbon solvents such as heptane, alicyclic hydrocarbon solvents, and the like. These solvents can be used alone or in combination.
[0026]
As another graft modification method different from the above method, there is a method in which a modified product is prepared by bringing a polyolefin into contact with an unsaturated carboxylic acid or a derivative thereof in the absence of a solvent using an extruder or the like. As for 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.
In order to efficiently copolymerize the graft monomer and unsaturated carboxylic acid or derivative thereof with the graph, it is preferable to use a radical initiator.
[0027]
Examples of radical initiators used for graft modification in the present invention include organic peroxides, organic peresters, and azo compounds. Examples of these include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, and di-t. -Butyl peroxide, 2,5-dimethyl-2,5-di (peroxide benzoate) hexyne-3,2,5-bis (t-butylperoxyisopropyl) benzene, t-butyl perbenzoate, t-butyl perphenyl acetate, Mention may be made of t-butyl perisobutyrate, t-butyl per-sec-octoate and t-butylbendiethyl acetate, azobisisobutyronitrile and the like. These radical initiators can be used alone or in combination. Among these, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t Dialkyl peroxides such as -butylperoxy) hexane and 1,4-bis (t-butylperoxyisopropyl) benzene are preferred. The radical initiator is usually used in an amount of 0.001 to 1 part by weight based on 100 parts by weight of the unmodified polyolefin.
[0028]
The graft amount (graft modification rate) of the graft-modified product obtained by graft modification in this manner is usually 0.05 to 10% by weight, preferably 0.05 to 5% by weight. 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. Therefore, in the present invention, graft modified products having a suitable graft modification rate can be used singly or in combination, and an unmodified polymer can be used in the graft modified products having a high graft modification rate to the above-mentioned suitable graft modification rate. It can also be added and diluted as such.
[0029]
Such a layer 15 can be formed of the above-mentioned graft modified product, but can be formed by using another resin together with or separately from the graft modified product. 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 / butadiene rubber, and isoprene rubber. it can. In addition, modified elastomers obtained by modifying these olefin elastomers with the unsaturated carboxylic acid or a derivative thereof can be used as well. 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, it can be used without particular limitation as long as the properties of the layer 15 are ensured. The amount is usually 30 parts by weight or less, preferably 20 parts by weight or less based on 100 parts by weight of the (co) polymer.
[0030]
Such a base material 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 and is at least two layers. The cost does not increase when it is layered.
When the base layer 10 has two layers, the modified polyolefin forming the layer 15 together with the unmodified polyolefin can be co-extruded to form a multilayer film, or a film forming the layer 15 can be separately manufactured. It can also be formed by stacking. Alternatively, the modified polyolefin, which is a component forming the layer 15, may be dissolved or dispersed in a solvent and applied onto the layer 12 to remove the solvent.
[0031]
The easily peelable packaging material of the present invention comprises various production methods, for example, thermoplastic resins such as low crystalline polyester that forms the sealing layer 20, modified polyolefins that form the base layer, and thermoplastic resins such as unmodified polyolefins. A method in which each is melted in a separate extruder and co-extruded using a multilayer die such as two or three layers, and manufactured by extruding and laminating a thermoplastic resin that forms a sealing layer on a pre-formed base layer film And the like. When using low crystalline polyester as the thermoplastic resin for forming the seal layer, it is preferable to employ a coextrusion molding method.
[0032]
In the present invention, the layer 15 can be preferably formed using a modified ethylene (co) polymer as described above, but separately, the surface of the unmodified polyolefin constituting the layer 12 is sealed. You may use what formed the surface laminated | stacked with the layer 20 by the method of processing with an energy ray, the method of making a surface react with a surface, for example.
[0033]
One preferred example of the easy-open packaging material of the present invention is a laminate of the base layer 10 thus formed with the layer 15 and the seal layer 20.
The seal layer 20 is preferably formed from a resin composition having a melting point of 200 ° C. or lower.
The film forming the seal layer 20 preferably has an elongation at break of 200% or more.
[0034]
  The film forming such a sealing layer 20 is usually formed from a low crystalline polyester composition. This low crystalline polyester composition is:Crystalline polyester AAnd a polyester composition containing amorphous polyester B. The melting point of the crystalline polyester A used in the present invention is usually 200 ° C. or less, preferably 90 to 185 ° C., and the glass transition temperature (Tg) is usually 40 ° C. or less, preferably −35 to 35 ° C. It is a resin in the range of 20 ° C. If 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 deteriorate due to heating during kneading, Since the melting point of the composition with the crystalline polyester B is also increased, it may be difficult to form a film. Furthermore, when such a resin is used, it is necessary to set the heat sealing temperature high, and there is a possibility that the opening property of the resulting packaging material may be lowered. 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 lowered in the present invention.
[0035]
As another characteristic of such crystalline polyester A, the reduced viscosity measured for the crystalline polyester A is usually in the range of 0.5 to 2.5, preferably 0.6 to 2.0, and the weight The average molecular weight is usually in the range of 20,000 to 350,000, preferably 30,000 to 300,000.
Examples of such crystalline polyester A include a polyester obtained by polycondensation of a dicarboxylic acid and a diol. Examples of the dicarboxylic acid used here include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, aromatic carboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and diphenylcarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. Mention may be made of acids. Examples of the diol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like.
[0036]
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 diol component having a relatively long carbon chain is used as a diol component. Used for condensation polymerization. Crystalline polyester A having such characteristics is already commercially available, and as crystalline polyester A having the above characteristics, for example, it is commercially available under the trade name “Byron” (manufactured by Toyobo Co., Ltd.). Crystalline polyesters can be used.
[0037]
Amorphous polyester B used in the present invention is based on polyethylene terephthalate, and may use a dicarboxylic acid other than terephthalic acid as the dicarboxylic acid component, and a glass transition temperature of a polyester other than ethylene glycol as the diol component. Polyethylene terephthalate copolymer polycondensed using 1,4-cyclohexanedimethanol as part of the diol component, preferably a part of the diol component. Examples of dicarboxylic acid components other than the terephthalic acid component used here include aromatic dicarboxylic acids such as isophthalic acid and diphenylenecarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid. Examples of diol components other than ethylene glycol and 1,4-cyclohexanedimethanol include propylene glycol and 1,4-butanediol. Specific examples of such an amorphous polyester resin include a condensation polymer of ethylene glycol and terephthalic acid, a condensation polymer of ethylene glycol, isophthalic acid and terephthalic acid, and 1,4-cyclohexanedimethanol. Examples include condensation products of isophthalic acid and terephthalic acid, condensation polymerization of ethylene glycol, 1,4-cyclohexanedimethanol, isophthalic acid and terephthalic acid, and condensation polymerization of propylene glycol, isophthalic acid and terephthalic acid. it can.
[0038]
The weight average molecular weight of such amorphous polyester B is usually in the range of 10,000 to 400,000, and the glass transition temperature (Tg) is usually above 40 ° C, preferably in the range of 45 to 90 ° C. Is in. And since this amorphous polyester B does not have crystallinity, when it is used independently, it does not crystallize in the process of heating and cooling. In particular, the present invention uses a copolyester resin in which at least a part of component units derived from ethylene glycol forming polyethylene terephthalate is replaced with component units derived from 1,4-cyclohexanemethanol as amorphous polyester B. It is preferable to do.
[0039]
  Such an amorphous copolyester-based resin is already commercially available. In the present invention, for example, as the amorphous polyester B having the above-mentioned characteristics, a trade name of “PET-G” (Eastman Amorphous copolyester resins commercially available from Kodak Company) can be used. In the present invention, a resin composition in which the crystalline polyester A and the amorphous polyester B are preferably mixed is used. That is, the crystalline polyester A and the amorphous polyester B are melt-kneaded to form a heat-sealable composition, and the heat-sealable composition is used to form a heat-seal layer on the substrate surface. This heat-sealable composition comprises the above crystalline polyester A.70 to 90 parts by weightAmorphous polyester B is used in an amount within the range of10-30 parts by weightUse in an amount within the range. The low crystalline polyester composition comprising the crystalline polyester A and the amorphous polyester B at the blending ratio as described above is particularly excellent in low temperature heat sealability with the polyester sheet or polycarbonate, and peels off the sealed portion 40. In this case, for example, as shown in FIG. 3, since delamination occurs, it has a characteristic that it is excellent in the sealing property of impurities.
[0040]
The low crystalline polyester resin composition, which is a preferred example of the thermoplastic resin forming the sealing layer 20 of the easy-open packaging material 1 of the present invention, has a melting point of usually 200 ° C. or lower, preferably 180 ° C. or lower, especially Preferably it exists in the range of 70 to 180 degreeC. By using such a low crystalline polyester having a melting point, good heat seal strength is exhibited at a low temperature, and even if the heat seal temperature is increased, the heat seal strength is not significantly increased.
[0041]
Various additives that are usually added to the thermoplastic resin forming the seal layer 20 of the easy-open packaging material 1 of the present invention, such as heat resistance stabilizer, slip agent, antistatic agent, antiblocking agent, ultraviolet absorber Additives such as weathering stabilizers, light stabilizers, anti-fogging agents, nucleating agents, lubricants, dyes that only absorb light of a specific wavelength, pigments, natural oils, synthetic oils, waxes or translucent fillers Can be blended.
[0042]
In particular, the easy-open packaging material of the present invention supplies a film raw material supplied in a wound state to a processing device and processes it into a predetermined form, so that the film raw material can be stably supplied to the processing device. Therefore, it is preferable to add an antistatic agent, an antiblocking agent and a slip agent to the thermoplastic resin forming the sealing layer. Such additives are usually blended 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 the antiblocking agent, the 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.
[0043]
In particular, it is preferable to add an antiblocking agent and an antistatic agent to the thermoplastic resin forming the seal layer used in the present invention.
Examples of antiblocking agents used herein may include silica powder, calcium carbonate, calcium silicate and aluminum silicate, and examples of antistatic agents include glycerin higher fatty acid mono- or diesters, and And diglycerin higher fatty acid mono- or diester.
[0044]
Furthermore, examples of slip agents that may be used in the present invention include higher fatty acid amides such as erucic acid amide and oleic acid amide, and higher fatty acid bisamides such as ethylene bisoleic acid amide and ethylene biserucic acid amide. Can be mentioned.
The sealing layer 20 formed from a thermoplastic resin composed of the above components usually has a thickness of 10 μm or less, preferably 3 to 8 μm.
[0045]
The seal layer 20 of the easy-open packaging material 1 of the present invention is preferably formed from the low crystalline polyester composition as described above, and the elongation at break of the film forming the seal layer 20 is measured. Then, the elongation at break (breaking elongation) of this film is usually 200% or more, preferably 350% or more, and particularly preferably in the range of 350% to 450%. When a film made of a low crystalline polyester composition in which the specific crystalline polyester A and the amorphous polyester B described in the present invention are blended in a specific ratio is used, the sealing layer 20 has such a high elongation at break. In spite of the fact that the easy-open packaging material of the present invention is used as a container lid material, it is possible to perform a strong heat seal that causes delamination without causing the contents to leak during transportation, etc. When taking out a thing, it has the characteristic that it can peel easily by delamination.
[0046]
And the easy-open packaging material 1 of this invention has the outstanding blocking resistance, and after winding and holding the film, the film which forms the easy-open material 1 unwinded was wound. It has excellent properties that it can be easily peeled off from the film and does not require great force for unwinding the film.
This blocking resistance is quantitatively confirmed by closely adhering the seal layer 20 that is most likely to cause blocking and adjusting the blocking resistance measurement sample to determine the peel strength between the seal layers 20 and 20. be able to.
[0047]
That is, a test piece was cut out from the easy-open packaging material of the present invention, two test pieces were stacked so that the seal layer 20 faced, and a load of 25 kg was applied to the area of this test piece 100 mm × 100 mm at 50 ° C. Leave for 72 hours. Next, when the peel strength of the above test piece is measured using a peel strength measuring device in which the chuck-to-chuck speed is set to 200 mm / min, the peel strength of the easy-open packaging material of the present invention is preferably 1 N / 100 mm or less. Shows a very low value in the range of 0.1 to 0.5 N / 100 mm. Therefore, the easy-open packaging material of the present invention is less likely to be blocked in the film that has been wound and stored after production, and the easy-open packaging material is used to laminate the layer 22 such as stretched polyester resin or stretched polyamide resin. Thus, troubles such as rewinding are less likely to occur and a good film can be produced.
[0048]
The easy-open packaging material of the present invention is laminated on the base layer 10 as described above (which may be composed of two layers of a modified polyolefin layer and an unmodified polyolefin layer). Further, the easy-open packaging material 1 of the present invention may have a layer 22 disposed on the surface where the seal layer 20 is not formed, as shown in FIG. 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.
[0049]
This layer 22 can be formed of paper, non-woven fabric, resin film, metal foil, metal-deposited foil, and the like conventionally used as packaging materials, and also uses these composites (laminates). Can do.
In particular, in the present invention, it is preferable to use a resin film as the layer 22, and examples of the resin film forming this layer include a uniaxial or biaxially stretched polyamide film (eg, nylon 6, nylon 66, etc.), uniaxial or Biaxially stretched polyester film (eg, polyethylene terephthalate film) can be mentioned.
[0050]
This layer 22 is usually laminated on the base layer 10 via the adhesive layer 16. The adhesive layer 16 can be formed of an adhesive having adhesiveness equivalent to that of the base layer 10 or the layer 15. The layer 22 may be formed by using a method such as dry lamination, extrusion lamination, or sandwich lamination when laminating the low crystalline polyester composition / modified polyolefin / unmodified polyolefin, for example. it can.
[0051]
When the easy-open 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. Moreover, when laminating | stacking the layer 22 on this easy-open packaging material through the adhesive bond layer 16, the thickness of this adhesive bond layer 16 is 3-20 micrometers normally, Preferably it is 3-10 micrometers.
[0052]
The easy-open packaging material 1 of the present invention can be manufactured by employing various lamination methods such as conventional lamination methods such as coextrusion lamination method, extrusion coating method, and thermal lamination method.
The easy-open packaging material of the present invention can be particularly suitably used as, for example, an easy-open lid material. In addition, easy-open packaging materials using heat-sealable compositions containing polyolefin resins (surface film-forming compositions) have good heat-seal properties against polyethylene terephthalate, polyethylene naphthalate, and polycarbonate substrates. In addition, it shows excellent easy-opening properties particularly when heat-sealed with these substrates. However, favorable easy-openability can be expressed also by adjusting the heat seal conditions for the adherends formed from other resins.
[0053]
The easy-open packaging material of the present invention can be placed so that the sealing layer faces and heat-sealed to form a bag-like package, or it can be used as a container lid.
FIG. 3 is a view showing a state where the lid made of the easy-open packaging material 1 of the present invention is heat-sealed on the upper edge of the sheet (other material) 30 serving as a container and then peeled off. In FIG. 3, the number 40 represents a heat seal part.
[0054]
The easy-open packaging material of the present invention preferably has the structure shown in FIG. 2, and a sealing layer 20 made of a low crystalline polyester composition is heat-sealed at the edge of the upper surface of the container.
When peeling off such a lid, the lid can be easily peeled by delamination between the modified polyolefin layer 15 constituting the base layer 10 and the seal layer 20.
[0055]
【The invention's effect】
The easy-open packaging material of the present invention is less susceptible to blocking in the film that has been wound and stored after production, and in this step of bonding with the layer 22 such as stretched polyester resin or stretched polyamide resin using this easy-open packaging material, The occurrence of troubles such as rewinding is small, and a good film can be produced. Further, by using a thermoplastic resin made of a specific low crystalline polyester composition containing a crystalline polyester resin and an amorphous polyester resin as a sealing layer and using a modified polyolefin layer as a base layer, the sealing layer is relatively low. Sufficient heat-sealing strength is achieved to express easy peelability from the temperature, and even if the heat-sealing temperature is high, it peels off between the low crystalline polyester composition layer and the modified polyolefin layer, thus maintaining easy opening. And the heat seal strength does not become extremely high.
[0056]
Further, according to the present invention, it has a good heat heel property for polyesters such as polyethylene terephthalate and polyethylene naphthalate, or polycarbonate, and is easy to open when heat-sealed with a container made of these resins. Heat seal strength can be achieved.
Furthermore, when the low crystalline polyester composition is used as the seal layer, the composition is located in the innermost layer, and therefore, the fragrance retention is excellent.
[0057]
【Example】
The following description of the easy-open packaging material of the present invention will be made with specific examples, but the present invention is not limited thereto.
[0058]
[Example 1]
As the crystalline polyester A, the melting point is 123 ° C., the glass transition temperature (Tg) is −70 ° C., the weight average molecular weight is 30,000 to 40,000, and the density is 1.26 g / cm.^ThreeCrystalline polyester (trade name: Byron_TM GM913, manufactured by Toyobo Co., Ltd.) was prepared.
[0059]
Apart from this, as amorphous polyester B, the glass transition temperature (Tg) is 81 ° C., the weight average molecular weight is 26000, the intrinsic viscosity is 0.75, and the density is 1.27 g / cm.^ThreeAmorphous polyester (trade name: PET-G_TM6763, manufactured by Eastman Kodak Company).
With respect to 90 parts by weight of the above crystalline polyester A, 10 parts by weight of amorphous polyester B, and 100 parts by weight of these resins in total, an antistatic agent (trade name: Chemistat)_TM PEG6000, manufactured by Sanyo Chemical Industries Co., Ltd.) 0.4 parts by weight and 0.5 parts by weight of silica powder having an average particle size of 3.0 μm as an antiblocking agent are melt-kneaded to form a surface layer of a low crystalline polyester composition A product (resin composition forming a heat layer) was prepared.
[0060]
The amorphous polyester B is polyethylene terephthalate in which a part of ethylene glycol of polyethylene terephthalate produced from terephthalic acid and ethylene glycol is replaced with 1,4-cyclohexanedimethanol.
High-pressure low-density polyethylene (trade name: Mirason)_TMM12P, manufactured by Mitsui Chemicals, MFR: 3 g / 10 min, density: 0.927 g / cm^Three) Was prepared.
[0061]
As a base layer, a modified polyolefin forming a layer to be laminated with a seal layer is a polyethylene / 1-octene random copolymer (A) (MFR (190 ° C.): 4 g / 10 min, density: 0.920 g / cm^Three), Ethylene-propylene random copolymer (B) (ethylene content: 70 mol%, density: 0.870 g / cm^Three), Maleic anhydride graft-modified polyethylene (C) (maleic anhydride content: 1% by weight, density: 0.960 g / cm^ThreeAnd (A) / (B) / (C) = 65/5/30% by weight in a Henschel mixer, and then granulated to prepare a modified polyolefin.
[0062]
Three layers of the above three components were coextruded to form a three-layer film that was an easy-open packaging material. The co-extrusion conditions at this time were as follows: a low crystalline polyester composition serving as a seal layer, a modified polyolefin as one of the base layers, and a high-pressure low-density polyethylene as another base layer were simultaneously co-extruded at an extrusion temperature of 230 ° C. Extrusion conditions were set.
The thickness of each layer of the obtained three-layer film composed of a seal layer / base layer (modified polyolefin layer) / base layer (unmodified polyolefin layer) was 5 μm / 10 μm / 15 μm.
[0063]
Next, the obtained co-extruded three-layer film was laminated by high pressure low density polyethylene (back surface) and biaxially stretched polyamide film (ONy) having a thickness of 15 μm by dry lamination using a urethane adhesive. A lid material which is an easy-open packaging material of the invention was produced.
〔Evaluation methods〕
In the examples of the present invention, various evaluations were performed by the following methods.
1) Heat seal strength
The seal layer (low crystalline polyester layer) surface of the easy-open film produced by the above method is layered on an amorphous polyester resin sheet (trade name: Orphan PET sheet, manufactured by Osaka Resin Chemical Co., Ltd.) with a thickness of 220 μm. And heat sealed under the following conditions.
[0064]
Seal bar temperature: listed in Table 1
Pressure: 0.2 MPa
Seal bar width: 5mm
Sealing time: 1 second
Next, the test piece obtained by the above method was subjected to a T-shaped peel test with a universal testing machine at a pulling speed of 500 mm / min, and the average strength value (N / 15 mm) was defined as the heat seal strength.
2) Contaminant sealability
Using an easy-open packaging material, a 100 mm × 200 mm three-way heat-sealed bag product was manufactured. A pickled kimchi containing water was added from the opening, and the bag was closed by heat sealing. The state of the seal part and liquid leakage were evaluated.
3) Blocking strength (peel strength)
The method was performed according to ASTM-D1893. That is, a load of 25 kg was placed on an area of 100 mm × 100 mm on a rectangular sample of 150 × 100 mm and left in an air oven at 50 ° C. for 3 days (72 hours). The blocking strength was expressed as strength (peel strength) (N / 100 mm) when the sample was peeled at a speed of 200 mm / min.
4) Elongation at break of low crystalline polyester composition film
A cast film having a thickness of 50 μm made of a polyester composition having the composition described in Examples and Comparative Examples was prepared, a tensile test piece was cut out from the film, a tensile test was performed according to the method of ASTM-D882, and the breaking point was obtained. The elongation was determined. The tensile test was performed under the condition of a tensile speed of 300 mm / min.
[0065]
The results are shown in Table 1.
[0066]
[Examples 2 to 5]
Byron which is crystalline polyester A in Example 1_TMAmount and amorphous polyester B PET-G_TMAnd the easy-open packaging material was manufactured similarly except having changed the compounding quantity of an antistatic agent and fine powder silica as shown in Table 1.
[0067]
About the obtained easy-open packaging material, it carried out similarly to Example 1, and evaluated each performance.
The results are also shown in Table 1.
[0068]
[Comparative Examples 1-6]
Byron which is crystalline polyester A in Example 1_TMAmount and amorphous polyester B PET-G_TMAnd the easy-open packaging material was manufactured similarly except having changed the compounding quantity of an antistatic agent and fine powder silica as shown in Table 1.
[0069]
About the obtained easy-open packaging material, it carried out similarly to Example 1, and evaluated each performance.
The results are also shown in Table 1.
[0070]
[Table 1]

[0071]
As apparent from Table 1 above, the packaging material that satisfies the requirements of the present invention has a blocking strength of 1 N / 100 mm or less, and is excellent in processability and laminating characteristics during film production and cutting. In addition, as shown in FIG. 3, the packaging material satisfying the requirements of the present invention is delaminated at the heat seal portion 40 when peeled after being sealed, and is excellent in contaminant sealing properties, and when taking out the contents. Good openability.
On the other hand, as shown in FIG. 4, the packaging materials of Comparative Examples 1 to 5 are heat-sealed to the other material 30, and when this heat-sealed portion 40 is peeled off, interfacial peeling occurs, resulting in poor contaminant sealability. Furthermore, the packaging materials satisfying the requirements of the present invention have little variation in heat seal strength when heat sealed at 125 ° C. and when heat sealed at 130 ° C., whereas the packaging materials of Comparative Examples 1 to 5 are heat sealed. The heat seal strength varies greatly with temperature.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing an example of the configuration of an easy-open packaging material of the present invention.
FIG. 2 is a cross-sectional view schematically showing another example of the structure of the easy-open packaging material of the present invention.
FIG. 3 is a cross-sectional view schematically showing an example in which a heat-sealed portion is peeled after heat-sealing with another material using the easy-open packaging material of the present invention.
FIG. 4 is a cross-sectional view schematically showing an example in which the heat-sealed portion is peeled after heat-sealing with another material using the easy-open packaging material shown in the comparative example.
[Explanation 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 ... Back layer
30 ... Other materials
40 ... Heat seal part

Claims (7)

An easy packaging material comprising at least two thermoplastic resin layers having a base layer and a seal layer, wherein the seal layer is
Dicarboxylic acid unit having a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid, and a diol having a component unit derived from ethylene glycol and a component unit derived from 1,4-butanediol 70 to 90 parts by weight of crystalline polyester A having a glass transition temperature of 40 ° C. or lower, which is a polyester composed of repeating units composed of component units ;
Dicarboxylic acid component unit having a component unit derived from terephthalic acid and a component unit derived from an aliphatic dicarboxylic acid, and a diol component unit having a component unit derived from ethylene glycol and a component unit derived from cyclohexanedimethanol A non-crystalline polyester B having a glass transition temperature of 45 to 90 ° C. , which is a polyester composed of repeating units consisting of : A sealing layer containing 10 to 30 parts by weight (the total of A and B is 100 parts by weight) Yes,
The seal layer is peeled off while leaving the seal layer on the heat-sealed adherend, and the seal layers are overlapped with each other and left to stand at 50 ° C. for 72 hours with a load of 25 kg applied to an area of 100 mm × 100 mm. The peel strength peeled at a speed of 200 mm / min is 1 N / 100 mm or less,
An easy-open packaging material characterized in that the adherend is a container made of a polyester-based resin or a container made of a polycarbonate-based resin . The low crystallinity thickness of the surface layer made of a polyester composition, easy-open packaging material as in claim 1 wherein, wherein the at 10μm or less. The easy-open packaging material according to claim 1, wherein the thermoplastic resin constituting the base layer is formed from a modified polyolefin. 4. The openable packaging material according to claim 1, wherein the base layer is composed of at least two layers of an unmodified polyolefin and a modified polyolefin, and the modified polyolefin layer is in contact with the seal layer. 5. The easy-open packaging according to claim 3 , wherein the modified polyolefin is a modified polyolefin partially or entirely graft-modified with an unsaturated carboxylic acid or a derivative thereof. material. The stretched polyethylene terephthalate film and / or the stretched polyamide film are laminated on the surface of the modified polyolefin layer forming the base layer or the base layer surface of the polyolefin layer and the modified polyolefin layer on which the seal layer is not laminated. The easy-open packaging material according to any one of Items 3 to 5 . The easy-open packaging material according to any one of claims 1 to 6 , wherein the easy-open packaging material is a container lid material.

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