JP2001277416A - Easy peel laminate and method of manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy peel laminate reconciling hermetic sealability at the time of sealing and easy peelability at the time of opening, realizing an extremely homogenous and smooth peel feeling and excellent in the sealability of the laminated stepped part of a paper container or the like, and a method for manufacturing the same. SOLUTION: The easy peel laminate has a sealant layer (A) and a cushioning layer (B) having melt elasticity and the cushioning layer is desirably composed of a crosslinkable resin composition containing (b1) an ethylenic copolymer containing ethylene and radical polymerizable acid anhydride as essential constituents, (b2) a polyhydric alcohol compound having two or more hydroxyl groups in its molecule and (b3) a reaction accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to packaging materials used in the fields of foods, electronic parts, industrial materials, daily necessities, etc.
The sealability at the time of sealing and the easy peeling property (easy peeling property) at the time of opening are both compatible, and the opening can be performed uniformly and smoothly (the peeling surface at the time of opening is beautiful, there is no stringing phenomenon, etc. (The resistance is uniform and has an optimum value).

[0002]

2. Description of the Related Art In various fields such as foods, electronic parts, industrial materials, and daily necessities, a packaging laminate having a sealant layer (heat seal layer) having a good sealability for protecting and preserving the contents has been developed. It is used as a lid material and a container body. Such a laminate is required to have a sufficient sealing strength when sealed by heat sealing. However, such laminates include those that are difficult to open or cannot be opened manually. In recent years, such packaging laminates have been required to satisfy not only the sealing strength (sealing property) at the time of sealing but also the easy peel property (easy peeling property) that can be easily opened at the time of opening. Various easy-peel laminates having both practical sealing properties and easy-peel properties have been put to practical use.

[0003] Such an easy-peelable laminate is an excellent packaging material widely used all over the world regardless of food or non-food. The packaging form using this laminate is
It is expanding for purposes such as hygiene management, quality management, and safety management. As such a packaging form, for example, in the food field, a deep-drawn container body (bottom material) containing meat, sliced ham, and the like and a lid material made of an easy-peelable laminate are heated around the container body. Sealed packaging form,
A packaging form in which a cup-shaped container main body containing pudding, yogurt, and the like and a lid member made of an easy-peelable laminate are heat-sealed at the opening peripheral portion of the container main body.

As the application range of the easy-peelable laminate is diversified, high performance and high function are increasingly required. For example, in the food field, materials having higher hardness such as polypropylene, polystyrene, and polycarbonate are widely used as container bodies. However, when a lid material made of an easy-peel laminate is sealed to such a container body having a low cushioning property, a part having a strong sealing strength and a part having a weak sealing force are inevitably generated, so that it cannot be uniformly peeled at the time of opening. It is difficult to obtain a sufficiently smooth peeling feeling. Thus, in the food field, there is a demand for an easy-peelable laminate that can be opened uniformly and smoothly at the time of opening.

[0005] From the viewpoint of preventing leakage of contents, sealing conditions are often adjusted so that sufficient sealing strength is obtained in a portion where the sealing strength tends to be weakest. Therefore, the seal strength in a portion where the seal strength tends to be strong is too strong than the appropriate seal strength. When opening a packaging container with a part with excessively strong sealing strength, there are few cases where the contents are splattered when trying to open it forcibly, and it is difficult for infants and elderly people with weak hands to open it. Absent. In addition, a system in which foods, assembled parts, and the like are automatically supplied by an automatic opening robot incorporated in a manufacturing process regardless of food or non-food has become widespread in a specific field.
In the field of such use, an extremely peelable laminate and a strictly uniform peel strength are required for an easy-peelable laminate.

Further, in a paper container such as a paper cup, a step is generated in a portion where the paper and the paper are bonded, so that there is always a bonding step on the surface to be sealed on the paper container side. At present, an easy-peel laminate capable of filling this step portion with a seal without extremely increasing the thickness of the sealant layer is an ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) -based hot melt. Only those using a group of resins referred to as sealant layers.

[0007]

As described above, the needs for an easy-peeling laminate in recent years have been diversified extremely. Among them, a smooth peeling feeling and a sealing property at a step portion of a paper container to be stuck are included. These two points can be said to be typical needs that exist in the easy peel field.
Various attempts have been made to meet these needs, but at present, smooth easy peeling is maintained by extremely increasing the thickness of the sealant resin or reducing the seal strength.

Further, an EVA-based hot melt which satisfies the sealing property of a step portion of a paper container to be bonded is also disclosed.
Basically, in order to maintain the sealing strength, it is necessary to extremely increase the flow or lower the heat resistance. Therefore, its use is restricted in applications where the temperature is high at the time of filling or sealing the contents, or in applications where even a small amount of acetic acid is difficult to mix. As described above, a sealant resin that can sufficiently satisfy the above two major needs has not been proposed yet.

Accordingly, an object of the present invention is to achieve both a sealing property at the time of sealing and an easy peeling property at the time of opening, realize an extremely uniform and smooth peeling feeling, and provide a stepped portion for bonding a paper container or the like. It is an object of the present invention to provide an easy-peelable laminate excellent in sealing properties and a method for producing the same.

[0010]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a buffer layer made of a cross-linked polyolefin or the like which functions as a cushion material at the time of sealing is made of a sealant resin. By providing an indirect or direct contact with the sealant layer on the side opposite to the sealing surface, it is possible to realize a very uniform and smooth peeling feeling and to realize excellent sealing properties at the bonding step portion of a paper container or the like. The present invention led to the heading.

That is, the easy-peelable laminate of the present invention is characterized by having a sealant layer (A) and a buffer layer (B) having melt elasticity. Further, it is desirable that the sealant layer (A) and the buffer layer (B) having melt elasticity are in direct contact with each other. Further, the easy-peelable laminate of the present invention preferably further has a base material layer (C). The buffer layer (B) having melt elasticity is preferably made of a polyolefin-based cross-linking material.

The polyolefin-based cross-linking material includes (b1) an ethylene-based copolymer having ethylene and a radical polymerizable acid anhydride as essential components, and (b2) a polyvalent compound having two or more hydroxyl groups in a molecule. An alcohol compound, and (b3) a reaction accelerator, wherein the proportion of units derived from the radically polymerizable acid anhydride in the (b1) ethylene-based copolymer is 0.1 to 20% by weight; (B
1) With respect to the acid anhydride group in the ethylene copolymer, (b)
2) The molar ratio of hydroxyl groups derived from the polyhydric alcohol compound is
The resin composition is in the range of 0.01 to 10 and the (b3) reaction accelerator is in the range of 0.001 to 20 parts by weight with respect to (b1) 100 parts by weight of the ethylene copolymer. It is desirable.

As a method for producing the easy-peelable laminate of the present invention, an extrusion laminating method, a co-extruded film method, a laminating method using a dry laminator after film formation, and the like are used. The extrusion laminate molding method is suitably used in that a laminate comprising at least two layers including a buffer layer (B) having melt elasticity is efficiently produced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The sealant resin used for the sealant layer (A) in the present invention is not particularly limited. In the easy-peelable laminate of the present invention, the effects of the present invention can be exhibited regardless of the type of the sealant resin. The point that there is no need to particularly limit the sealant resin is one of the excellent points in the present invention.

Examples of the sealant resin that can be used in the present invention include the following commercially available sealant resins. Although details of the components of these sealant resins are unknown, general commercially available sealant resins include CMPS series manufactured by DuPont Mitsui, CMPS film series manufactured by Tosero, Hirodine series manufactured by Yasuhara Chemical, Tosoh Corporation Mersen series manufactured by Mitsubishi Chemical (Wada Chemical), DMX Thermo series manufactured by Dainippon Ink and Chemicals, Dyamide series manufactured by Daicel Chemical, API series manufactured by DuPont, Nippon Polyolefin Co., Ltd. Lexpearl E
T series and the like.

The resin used in the buffer layer (B) having melt elasticity in the present invention is not particularly limited as long as it is a resin having melt elasticity. Here, the resin having melt elasticity is a resin that is not completely melted under the sealing temperature condition and has a state of being softened but keeping its shape to some extent. Examples of the resin having such a melt elasticity include a polyolefin-based crosslinked material, a thermoplastic elastomer, and a synthetic rubber. Among them, a polyolefin-based crosslinked material is preferably used in terms of extrusion lamination processing suitability, performance, economy and the like.

The polyolefin-based cross-linking material is a resin obtained by cross-linking a polyolefin-based resin by various cross-linking methods. The polyolefin base resin is not particularly limited, but specifically, high-density polyethylene, low-density polyethylene (LDPE), linear low-density polyethylene, ethylene-vinyl acetate copolymer (EV
A), ethylene-methyl acrylate copolymer (EM
A), ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-maleic anhydride copolymer, ethylene-maleic anhydride- (meth) acrylate copolymer, ethylene-α- Examples include olefin copolymers, metallocene catalyst-based polyethylene, maleic anhydride-modified polyethylene, and maleic anhydride-modified polypropylene.

The method for crosslinking the polyolefin-based resin is not particularly limited, and examples thereof include an electron beam crosslinking method, a silane crosslinking method, a method using a peroxide, and a method using a crosslinking agent. Among them, a method using a peroxide and a method using a crosslinking agent are typical examples. As a method using a peroxide, a method in which a peroxide is added to the base resin within a range that does not adversely affect the molding, a method of crosslinking when molding the base resin, and a method in which a peroxide having a relatively high decomposition temperature is added. After the base resin is molded at a low temperature, a method of sufficiently crosslinking in a heat treatment step can be used. Specific examples of the crosslinking agent used in the method using the crosslinking agent include polyvalent amines, polyhydric alcohols, polyvalent epoxy compounds, polyvalent silane compounds, metal carboxylate, and the like.

As the polyolefin-based cross-linking material, a thermoplastic cross-linking resin (hereinafter, referred to as RC resin) proposed by Nippon Polyolefin Co., Ltd. is also preferably used in terms of proper extrusion lamination. You. The RC resin is (b1) an ethylene copolymer having ethylene and a radical polymerizable acid anhydride as essential components, (b2) a polyhydric alcohol compound having two or more hydroxyl groups in a molecule, and (b3) a reaction. (B1) the proportion of units derived from the radically polymerizable acid anhydride in the ethylene-based copolymer is 0.1 to 20% by weight,
1) With respect to the acid anhydride group in the ethylene copolymer, (b)
2) The molar ratio of hydroxyl groups derived from the polyhydric alcohol compound is
0.01 to 10 parts by weight, and the (b3) reaction accelerator refers to a resin composition in an amount of 0.001 to 20 parts by weight based on 100 parts by weight of the ethylene copolymer (b1). .

In the RC resin, the acid anhydride group contained in the (b1) ethylene copolymer reacts with the hydroxyl group contained in the (b2) polyhydric alcohol compound to form a monoester. By this reaction, a crosslinked structure is introduced into the resin composition. RC containing two components of (b1) an ethylene copolymer containing an acid anhydride group and (b2) a polyhydric alcohol compound
The resin exhibits properties as a so-called thermoplastic crosslinked resin in which a crosslinked structure is dissociated at a high temperature of 200 ° C. or higher and forms a crosslinked structure again upon cooling. Further, by adding (b3) a reaction accelerator, the rate of the crosslinking reaction or the rate of the crosslinking dissociation reaction can be increased. In this way, the RC resin dissociates and exhibits melt elasticity at a high temperature, which is a temperature range from the melting point of the resin for the buffer layer (B) to 200 ° C. or lower, and forms a cross-linked structure again upon cooling to provide heat resistance. It shows the properties and can be suitably used as a resin for the buffer layer (B).

The (b1) ethylene copolymer in the RC resin is a copolymer containing at least ethylene and a radically polymerizable acid anhydride as essential components, and if necessary, other radically polymerizable comonomers ( Hereinafter referred to as a third monomer)
May be copolymerized. Specific examples of the radical polymerizable acid anhydride used here include maleic anhydride, itaconic anhydride, citraconic anhydride, endic anhydride,
-Butene-3,4-dicarboxylic anhydride and the like. These may be used in combination of two or more. Of these, maleic anhydride is preferred in terms of reactivity and economy.

(B1) In the ethylene copolymer, the unit derived from the radically polymerizable acid anhydride is 0.1 to 20.
% By weight, preferably 0.3 to 5.0% by weight.
Range. If the unit derived from the radical polymerizable acid anhydride is less than 0.1% by weight, a sufficient crosslink density required for heat creep resistance cannot be obtained. In addition, 20% by weight
If it exceeds 3, the density between crosslink points will be too high, and reversible crosslink dissociation will not be performed smoothly.

(B1) As the ethylene copolymer, a copolymer obtained by copolymerizing a third monomer, if necessary, can be used. By copolymerizing the third monomer,
The melting point, flexibility, and compatibility with the adherend can be controlled, and a resin composition suitable for the purpose can be designed. Examples of the third monomer that can be used in combination with the radical polymerizable acid anhydride include an ethylenically unsaturated ester compound, an ethylenically unsaturated amide compound, an ethylenically unsaturated carboxylic acid compound, and an ethylenically unsaturated ether compound. And ethylenically unsaturated hydrocarbon compounds.

Specific examples of these third monomers include:
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, benzyl (meth) acrylate, methyl fumarate, ethyl fumarate, Dimethyl maleate, diethyl maleate, vinyl acetate,
(Meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethylacrylamide, (meth) acrylic acid, fumaric acid, methyl vinyl ether, methyl allyl ether, styrene, butadiene, acrylonitrile and the like can be mentioned. These third monomers are
If necessary, two or more kinds may be used simultaneously. Further, two or more copolymers using different third monomers may be polymerized, and these two or more copolymers may be mixed and used.

When the third monomer is used in combination, (b)
1) The content of the unit derived from the third monomer in the ethylene copolymer is in the range of 30% by weight or less, preferably 25% by weight or less. If it exceeds 30% by weight,
The melting point of the resin is too low, and practical heat resistance cannot be achieved.

(B1) The MFR of the ethylene copolymer is
Although there is no particular limitation, it is desirable that the range be 0.1 to 50 g / 10 minutes. (B1) MF of ethylene copolymer
If R exceeds 50 g / 10 minutes, the molecular pull-out resistance at the time of peeling is remarkably reduced, so that the heat creep resistance cannot be improved. If the MFR of the (b1) ethylene-based copolymer is less than 0.1 g / 10 minutes, the moldability (draw-down property) during extrusion laminating will be poor.

(B1) The ethylene copolymer can be produced by a generally known method, that is, a polymerization process such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Basically, it can be produced using ordinary low-density polyethylene production equipment and technology.

(B2) In the RC resin, two hydroxyl groups are present in the molecule.
Specific examples of the polyhydric alcohol compound having one or more
Ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, trimethylolethane, trimethylolpropane, pentaerythritol, albitol, sorbitol, xylose,
Glucose, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyolefin oligomer having two or more hydroxyl groups in one molecule, ethylene-hydroxyethyl (meth) acrylate copolymer, and other polymers having a plurality of hydroxyl groups in the molecule, Examples thereof include polyoxyalkylene compounds and polyglycerin esters obtained by adding ethylene oxide or propylene oxide to the above alcohol compounds.

The melting point of the polyhydric alcohol compound (b2) is desirably 300 ° C. or lower from the viewpoint of easy mixing with the (b1) ethylene copolymer. Also,
These (b2) polyhydric alcohol compounds may be used in combination of two or more.

The amount of the (b2) polyhydric alcohol compound used is such that the molar ratio of (b2) the hydroxyl group derived from the polyhydric alcohol to the (b1) acid anhydride group in the ethylene copolymer is as follows:
0.01 to 10, more preferably 0.05
~ 5. If the molar ratio is less than 0.01, the desired heat resistance cannot be obtained. When the molar ratio is 10
If it exceeds, the dissociation of the crosslinked structure at the time of heating is not sufficient, and the ratio of irreversible crosslinking increases, which makes molding difficult, which is not preferable.

Examples of the (b3) reaction accelerator in the RC resin include a metal salt of a carboxylic acid and a metal salt of a polymer containing a carboxyl group. Examples of metal salts of carboxylic acids include acetic, butyric, octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, behenic, succinic, benzoic, terephthalic, and pyromellitic acids. And carboxylic acids such as IA, IIA, IIB, and IIIB elements of the periodic table (for example, L
i, Na, K, Mg, Ca, Zn, Al, etc.).

Examples of the metal salt of the polymer containing a carboxyl group include a part or all of the carboxyl group of the ethylene- (meth) acrylic acid copolymer and a group IA or IIA of the periodic table.
Group, IIB, IIIB elements (eg, Li, Na, K,
(Mg, Ca, Zn, Al, etc.) or a copolymer of ethylene and a metal salt of ethylene- (meth) acrylate. At this time, the third monomer used in the (b1) ethylene-based copolymer may be used.

Further, a resin obtained by graft polymerization of a metal salt of an unsaturated carboxylic acid to a polyolefin resin such as polyethylene or polypropylene may be used.
(B3) Other examples of the reaction accelerator include triethylamine, trimethylamine, tetramethylammonium tetrafluoroborate, tetramethylammonium hexafluorophosphate, tetramethylammonium bromide, tetraethylammonium bromide and the like. Among the reaction accelerators exemplified above, metal carboxylate is preferably used in terms of easy handling and economy. In addition, two or more of the above-described reaction accelerators may be used simultaneously if necessary.

(B3) Since the amount of the reaction accelerator used varies depending on the type, it is difficult to define the amount in general. However, generally, (b1) 100 parts by weight of the ethylene copolymer is
The range is 0.001 part by weight or more and 20 parts by weight or less, more preferably 0.01 part by weight or more and 15 parts by weight or less. If the amount is less than 0.001 part by weight, the reaction is too slow to effectively introduce a crosslinked structure. If the amount exceeds 20 parts by weight, not only the reaction rate does not improve, but also the reversible crosslinking reaction does not easily proceed.

Various kinds of adhesive components can be added to the RC resin, if necessary, in the range of 1 to 25% by weight. Examples of the adhesive component used include cyclopentadiene-based hydrogenated petroleum resin,
Copolymer polyamide resin, terpene phenol resin, hydrogenated terpene resin, rosin resin, and the like. Various additives can be added to the RC resin as needed as long as the properties are not impaired. As a specific example,
Antioxidant (heat stabilizer), UV absorber (light stabilizer),
Examples include antistatic agents, lubricants, antiblocking agents, flame retardants, antifogging agents, inorganic fillers, pigments, and foaming agents.

The RC resin is an essential component (b1),
Although (b2) and (b3) are the main components, various polyolefin resins can be further blended according to the use and purpose. Specific examples of the polyolefin resin that can be blended include polyethylene, polypropylene, polystyrene, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer, and an ethylene-methyl acrylate copolymer.

The RC resin is an essential component (b1),
(B2), (b3) and, if necessary, an adhesive component, various additives, and a polyolefin to be added as an auxiliary component, such as an extruder, a Banbury mixer, a static mixer, a roll, etc.
It can be prepared by melt mixing by a general kneading method.

The easy-peel laminate of the present invention has two essential components, a sealant layer (A) made of a sealant resin and a buffer layer (B) made of a polyolefin-based cross-linking material and having melt elasticity. Things. The sealant layer (A) and the buffer layer (B) may be in direct contact with each other, or a third layer may be interposed therebetween. However, since the effects of the present invention, that is, the realization of a very uniform and smooth peeling feeling and the excellent sealing property at the bonding step portion, are considered to be achieved for the following reasons, the sealant layer (A) The thickness of the intermediate layer interposed between the sealant layer (A) and the buffer layer (B) is preferably 50 μm or less, and more preferably the sealant layer (A) and the buffer layer (B) are in direct contact with each other.

That is, the buffer layer (B) having melt elasticity in the easy-peelable laminate of the present invention is softened at the temperature at the time of heat sealing, but retains its shape to some extent. Since the buffer layer (B) in such a state functions as a cushion material, the sealing pressure at the time of sealing can be uniformly applied to the easy peel laminate and the adherend. Since the easy-peelable laminate can be uniformly sealed to the adherend in this manner, an easy-peelable laminate capable of realizing an extremely uniform and smooth peeling feeling can be obtained. In addition, since the buffer layer (B) functions as a cushioning material, even when the easy peel laminate is sealed at the bonding step portion of a paper container such as a paper cup, the sealant layer (A) has the shape of the step portion. And the sealing step can be filled with a seal.

Since the buffer layer (B) provided directly or indirectly on the side opposite to the sealing surface of the sealant layer (A) is considered to function as a cushion material under sealing conditions, the buffer layer (B) It is preferable to control the degree of crosslinking of the polyolefin-based crosslinking material used in the above to a low level. As a guide of the degree of crosslinking, the gel fraction is preferably less than 20%, more preferably less than 10%. The gel fraction was 0
%, A sufficient effect can be obtained as long as the resin flow under the sealing conditions is controlled. The standard in that case is MF
R (190 ° C.) less than 10 g / 10 min, preferably 5 g
/ 10 minutes or less.

The easy peel laminate of the present invention may further be provided with a base material layer (C). When the base material layer (C) is provided, the layer structure includes a sealant layer (A) / a buffer layer (B)
/ Substrate layer (C). Note that an intermediate layer may be provided between the sealant layer (A) and the buffer layer (B) or between the buffer layer (B) and the base material layer (C). Further, another layer may be provided as an outer layer further than the base layer (C).

As the base material used for the base material layer (C),
Paper, polyester, polyamide, saponified ethylene-vinyl acetate copolymer, polypropylene, polyvinylidene chloride resin and other films, nonwoven fabrics, woven fabrics, cellophane, stretched products of these, printed materials, aluminum, gold, silver, iron, steel,
Copper, nickel, metal foils such as alloys containing these as a main component,
A vapor-deposited film in which a metal such as aluminum or silicon or a metal oxide thereof is vapor-deposited on the surface of a film such as polyester or polyamide is exemplified.

The method for producing the easy-peelable laminate of the present invention is not particularly limited, but usually includes methods such as extrusion lamination, dry lamination, hot roll lamination, and frame lamination. Among them, an extrusion molding method such as extrusion lamination is preferable in terms of productivity.

When the buffer layer (B) is extrusion-laminated on the base material layer (C), an anchor coat treatment may be used in combination. Examples of the anchor coating agent used for the anchor coating treatment include an isocyanate anchor coating agent (urethane anchor coating agent), a polyethyleneimine anchor coating agent, a polybutadiene anchor coating agent, and an organic titanium anchor coating agent. The adhesive strength between the layer (C) and the buffer layer (B) is improved, and both are suitably used.

[0045]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Examples 1 to 10 and Comparative Examples 1 to 6 The resin composition for the buffer layer (B) having the composition shown in Table 1 was prepared at 180 ° C.
The mixture was melt-kneaded in the set twin screw extruder in the same direction. The resin of the comparative example was not used without the need for kneading. These resins were extrusion-laminated to a 30 μm thick aluminum foil base material at a resin temperature immediately below the die shown in Table 1 using an anchor coating agent of the type shown in Table 1 to a thickness of 15 μm. Further, the sealant resin in Table 1 was laminated thereon with a thickness of 20 μm,
A sample of the laminate was obtained. This sample was applied to the adherend shown in Table 1 at a temperature of 150 ° C. when using (A1) as the sealant resin, at 200 ° C. when using (A2) as the sealant resin, and at an air pressure of 2 kg / cm ^2. ,
Under a sealing condition of 0.5 seconds, heat sealing was performed, and smoothness of peeling and step sealability of the paper cup were evaluated.

[Smoothness of peeling] The smoothness of peeling was 9
The difference between the maximum peel strength and the minimum peel strength of the same sample when the 0 ° peel test was performed at 300 m / min was divided by the average adhesive strength and multiplied by 100, and the standardized value was used as the standard peel smoothness index. Was evaluated as follows. ◎: less than 1; ○: less than 10;
×: 50 or more

[Step Sealing Property of Paper Cup] The step sealing property of the paper cup was determined by heat-sealing a sample of the laminate under the conditions shown in Table 1 on a portion where a high quality paper assuming a paper cup was overlapped.
After the cross section of the step portion was cut out, red ink was applied to the cross section of the step portion, and evaluation was made based on the permeation of the ink by capillary action.
Table 1 shows the results. ○: No penetration, Δ: Penetration of less than 2 mm, ×: Penetration of 2 mm or more

[0049]

[Table 1]

The abbreviations in Table 1 are as follows. [Sealant resin for sealant layer (A)] A1: Nippon Polyolefin Co., Ltd., Lexpearl ET
808-3 A2: Montell SDK Sunrise Co., Ltd.
Made, sun allomer

[Each component of resin composition for buffer layer (B)] b11: ethylene-maleic anhydride (1.5% by weight)-
Methyl acrylate (25% by weight) terpolymer, MF
R = 12 g / 10 min b12: ethylene-maleic anhydride (2.0% by weight)-
Methyl acrylate (15% by weight) terpolymer, MF
R = 12 g / 10 min b21: 1,1,1-trimethylolpropane b22: tris (2-hydroxybutanoic acid) glycerin triester b31: ionomer (Himilan 1 manufactured by DuPont Mitsui)
605) b32: sodium stearate

RA3150: Nippon Polyolefin Co., Ltd.
Manufactured by Lexpearl RA3150 (ethylene-glycidyl methacrylate copolymer) EVA: manufactured by Nippon Unicar, NUC3461 (VA = 2)
0 wt%, MFR = 15 g / 10 min) (MFR = 7 g / 10 min) EMA: Lexpearl R, manufactured by Japan Polyolefin Co., Ltd.
B5200 (MA = 20% by weight, MFR = 10 g / 10
Minutes)

[Anchor Coating Agent] Imine: Nippon Shokubai Co., Ltd., polyethyleneimine anchor coating agent, Epomin P-1000, 1 wt% ethanol solution Urethane: Dainichi Seika Co., Ltd., urethane anchor coating agent, Yaikadyne 3600A 10 wt% + 3600B
4.6 wt% ethyl acetate solution [Coating material] HIPS: manufactured by Asahi Kasei Corporation, Styron 475D-H27 Homo PP: manufactured by Montell SDC Sunrise, Sun Allomer PM771M

In the laminate of Example 3, at the time of laminating the sealant layer (A), 5 μm of LDPE was coextruded and laminated with 15 μm of the sealant resin (A2) to form a laminate of the sealant layer (A) and the buffer layer (B). LDPE 5μm sandwiched between

[0055]

As described above, the easy-peel laminate of the present invention has the sealant layer (A) and the buffer layer (B) having melt elasticity. In addition to achieving both easy peelability and excellent uniformity and smoothness of peeling, excellent sealing properties at the stepped portion of a paper container or the like are obtained. Such an easy-peelable laminate can be applied to various fields including foods, industrial materials, electronic materials, and daily necessities. In particular, the easy peel laminate of the present invention,
It is significant in realizing an extremely smooth easy-peeling property required for the automatic opening process, and enabling an ideal easy-peel that can be easily opened even by a weak person and has no leakage of contents. In addition, because of the excellent sealing property of the bonding step portion, it is extremely effective as a key technology for enabling the development of the sealant resin even in the field of paper containers whose use has been restricted.

In the easy-peelable laminate of the present invention, if the sealant layer (A) and the buffer layer (B) having melt elasticity are in direct contact with each other, a smooth feeling of peeling or a step difference in bonding can be obtained. The sealing properties of the parts can be further improved. Further, if the buffer layer (B) having the melt elasticity is made of a polyolefin-based crosslinked material, good processing characteristics can be exhibited.

The polyolefin-based cross-linking material may be (b1) an ethylene-based copolymer having ethylene and a radical polymerizable acid anhydride as essential components, and (b2) a polyvalent compound having two or more hydroxyl groups in a molecule. An alcohol compound, and (b3) a reaction accelerator, wherein the proportion of units derived from the radically polymerizable acid anhydride in the (b1) ethylene-based copolymer is 0.1 to 20% by weight; (B
1) With respect to the acid anhydride group in the ethylene copolymer, (b)
2) The molar ratio of hydroxyl groups derived from the polyhydric alcohol compound is
The resin composition is in the range of 0.01 to 10 and the (b3) reaction accelerator is in the range of 0.001 to 20 parts by weight based on 100 parts by weight of the ethylene-based copolymer (b1). Thus, not only processing characteristics but also high productivity and economic efficiency can be obtained.

The method for producing an easy-peelable laminate of the present invention comprises producing a laminate comprising at least two layers including a sealant layer (A) and a buffer layer (B) having melt elasticity by an extrusion molding method. It is a method that achieves both the sealing property at the time of sealing and the easy peeling property at the time of opening, realizes extremely uniform and smooth peeling feeling, and has excellent sealing property at the bonding step part of paper containers etc. Thus, an easily peelable laminate can be produced very efficiently.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23/08 C08L 23/08 C09J 7/02 C09J 7/02 Z (72) Inventor Yoshio Suzuki Kawasaki, Kanagawa Research and development center, Technical Headquarters, Japan Polyolefin Co., Ltd., 2-3-2, Yakko 2-chome, Ichikawasaki-ku (72) Inventor Koji Okamoto 3-2-2, Yaiko, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan R & D, Japan Polyolefin Co., Ltd. F-term in the center (for reference) 3E067 AA11 AB01 AB04 AB05 AB41 BA07A BB01A BB06A BB11A BB15A BB16A BB25A BC07A CA24 CA30 EA06 GD03 GD08 4F100 AK03B AK04B AK04J AK12 AK21B02 AK21A00B07 AK21BAKA GB41 GB71 JK07B JK11B JL05 JL12 JL12B JL14 JL14A 4J002 BB081 BB091 EC0 46 EC056 EG017 EG027 EG037 FD157 GF00 4J004 AB03 CC03 FA06

Claims (6)

[Claims] 1. An easy-peel laminate comprising a sealant layer (A) and a buffer layer (B) having melt elasticity. 2. The easy-peelable laminate according to claim 1, wherein the sealant layer (A) and the buffer layer having melt elasticity (B) are in direct contact with each other. 3. The easy-peelable laminate according to claim 1, further comprising a base material layer (C). 4. The buffer layer (B) having melt elasticity,
The easy-peelable laminate according to any one of claims 1 to 3, comprising a polyolefin-based crosslinked material. 5. The polyolefin-based cross-linking material,
(B1) an ethylene copolymer having ethylene and a radical polymerizable acid anhydride as essential components, (b2) a polyhydric alcohol compound having two or more hydroxyl groups in a molecule, and (b)
3) containing a reaction accelerator, the proportion of units derived from the radically polymerizable acid anhydride in the (b1) ethylene-based copolymer is 0.1 to 20% by weight, and the (b1) ethylene-based The molar ratio of (b2) the hydroxyl group derived from the polyhydric alcohol compound to the acid anhydride group in the copolymer is in the range of 0.01 to 10, and (b3) the reaction accelerator is (b1) ethylene. The easy-peelable laminate according to claim 4, wherein the resin composition is in a range of 0.001 to 20 parts by weight based on 100 parts by weight of the system copolymer. 6. A process for producing an easy-peel laminate, comprising producing a laminate comprising at least two layers including a sealant layer (A) and a buffer layer (B) having melt elasticity by an extrusion molding method. Method.