JP2011046058A - Laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate in which at least an anchor coat layer, an adhesive layer, and a sealant layer are formed in turn on a metal foil base material such as aluminum foil etc., and which has good lamination strength, prevents the decline of the lamination strength between the metal foil base material and the sealant layer even when exposed to the action of a strongly permeable substance containing a volatile component, and can maintain good initial barrier properties. <P>SOLUTION: In the laminate, the anchor coat layer comprising a silane coupling agent, the adhesive layer comprising an isocyanate compound, and the sealant layer are formed in turn on the surface of the metal foil base material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  A laminate in which an anchor coat layer, an adhesive layer, and a sealant layer are provided at least in this order on a metal foil base material such as an aluminum foil, and has an excellent laminate strength, even if it contains a volatile component. The present invention relates to a laminate in which the initial excellent barrier property can be maintained without lowering the laminate strength between the metal foil base material and the sealant layer even when the permeable substance acts.

  When the contents to be packaged by the packaging material are liquid seasonings such as vinegar / oil, bathing agents (containing alcohol), poultices, etc., these contents are volatile with strong permeability such as fragrances and acids Since these substances are contained, when these contents are packaged using a conventional laminated type packaging material, the strong penetration of volatile substances causes a gap between the substrate and the sealant layer. There was a problem that the laminate strength decreased with time, resulting in delamination.

  As the adhesive for the adhesive layer constituting the laminated packaging material as described above, a two-component curable polyurethane-based adhesive is often used. The normal blending ratio of the curing agent made of an isocyanate compound is, for example, 95: 5 or 90:10, and the polyol is larger. However, the adhesive layer composed of the two-component curable polyurethane adhesive having such a blending ratio is affected by the strong penetrating contents as described above, which causes the polyol component to swell and the molecular weight to decrease, thereby reducing the cohesive force. For this reason, the laminate strength between the base material and the sealant layer has decreased over time.

  In addition, the adhesive layer made of a one-component isocyanate compound is likely to vary when cured, and the adhesiveness to the metal surface is weak, so a laminated structure packaging using a metal foil such as an aluminum foil with high barrier properties. When manufacturing a body, it had to be laminated | stacked through the plastic film with favorable adhesiveness between metal foil and an adhesive layer.

In order to cope with such a situation, for example, in Patent Document 1, as an adhesive used in laminating, a polyurethane resin having an NH group and an NH ₂ group and an excess amount of an organic isocyanate compound are reacted. We have proposed a method for producing packaging materials with excellent acid / alkali resistance.
Patent Document 2 proposes a method for imparting strong adhesion between a base material and a sealant of a laminated packaging material and resistance to a strong permeable material.

However, the type of laminate that uses metal foil as the base material and has a sealant layer laminated on its surface via an adhesive layer is excellent in barrier properties, so it is often used as a packaging material with good content preservation. However, the adhesive strength between the metal foil base material and the component layer on the metal foil base material is weak, and if a volatile substance with strong permeability such as fragrance or acid acts, the laminate strength between the metal foil base material and the sealant layer decreases. And may cause delamination.
Such a problem cannot be solved by the above-described proposal.

JP-A-10-130615 JP 2004-249656 A

  The present invention has been made in view of the situation as described above, and is resistant to volatile substances exhibiting strong permeability such as fragrances and acids in a laminate having a metal foil base material in part. It is an object of the present invention to provide a laminate that can be suitably used as a packaging material that can be applied and maintain excellent initial barrier properties even when a volatile substance acts.

  In order to solve the above problems, the invention according to claim 1 is characterized in that an anchor coat layer made of a silane coupling agent, an adhesive layer made of an isocyanate compound, and a sealant layer are arranged in this order on the surface of the metal foil base material. The laminate is provided at least.

  According to a second aspect of the present invention, in the laminate according to the first aspect, the sealant layer is made of any one of a polyethylene resin, a polypropylene resin, and an ethylene-propylene copolymer.

  Furthermore, in the invention according to claim 3, in the laminate according to claim 1 or 2, the constituent material of the adhesive layer is a bifunctional isocyanate monomer or a trifunctional type of adduct, biuret, or isocyanurate type. It is synthesized from a monomer derivative.

  Furthermore, the invention according to claim 4 is the laminate according to any one of claims 1 to 3, wherein the thickness of the adhesive layer is 0.01 μm or more and 1 μm or less.

  Furthermore, the invention according to claim 5 is the laminate according to any one of claims 1 to 4, wherein the surface of the metal foil base is subjected to an alkali cleaning treatment. .

The laminate of the present invention has a high laminate strength between the metal foil base material and the sealant layer, and has an excellent resistance to a highly permeable material.
Further, since the adhesive layer is composed of an isocyanate compound, the laminate strength is unlikely to deteriorate with respect to the highly permeable material.
Furthermore, since the anchor coat layer made of a silane coupling agent is provided on the surface of the base material, the adhesion between the metal foil base material and the sealant layer is high, and the initial excellent barrier properties are maintained. be able to.
Furthermore, when the thickness of the adhesive layer is a thin layer of 0.01 μm or more and 1 μm or less, strength deterioration due to variation in curing of the adhesive layer hardly occurs, and high adhesion can be maintained.
Then, by subjecting the surface of the metal foil base to an alkali treatment, the surface is moderately roughened and a coating film of the silane coupling agent is easily attached, and strong adhesion can be maintained.

It is explanatory drawing which shows the schematic cross-sectional structure of the laminated body of this invention.

  As shown in the drawings, the laminate of the present invention is provided with an anchor coat layer 2 made of a silane coupling agent, an adhesive layer 3 made of an isocyanate compound, and a sealant layer 4 in this order on the surface of the metal foil substrate 1. It is made.

Examples of the metal foil substrate 1 include a metal foil made of aluminum, copper, silver, or the like. An anchor coat layer 2 made of a silane coupling agent is provided on such a metal foil substrate 1, and examples of the silane coupling agent constituting this layer include the following.

  That is, γ-isocyanatopropyltriethoxysilane having an isocyanate group, γ-isocyanatopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane having an epoxy ring, γ-glycidoxypropyltrimethoxysilane Or γ-aminopropyltriethoxysilane having an amino group, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, and the like. .

  And it is the contact bonding layer 3 which consists of an isocyanate compound provided on the anchor coat layer 2 of such a structure. The adhesive layer 3 is a layer made of a constituent material synthesized from, for example, a bifunctional isocyanate monomer or a derivative of a trifunctional monomer of adduct, biuret, or isocyanurate type.

In the laminate of the present invention, as described above, the anchor coat layer 2 and the adhesive layer 3 are sequentially laminated on the surface of the metal foil substrate 1, and the sealant layer 4 is further laminated on the adhesive layer 3.
The sealant layer 4 is a thin film layer made of, for example, a polyethylene resin, a polypropylene resin, or an ethylene-propylene copolymer.

Since the laminated body of this invention is the above structures, it is excellent in the lamination strength between the metal foil base material 1 and the sealant layer 4, and shows the outstanding tolerance with respect to a highly permeable material.
Further, since the adhesive layer 3 is made of an isocyanate compound, the laminate strength is not easily deteriorated even if a highly permeable material acts.
Furthermore, since the anchor coat layer 2 made of a silane coupling agent is provided on the surface of the metal foil base material 1, the adhesion between the metal foil base material 1 and the sealant layer 2 is high, and the initial excellent Even if the strongly penetrating contents containing a fragrance and a medicinal component act on the barrier property or the like, it is not impaired.
And by making the thickness of the contact bonding layer 3 into a thin layer of 0.01 μm or more and 1 μm or less, strength deterioration due to variation in curing of the contact bonding layer 3 hardly occurs, and high adhesion can be maintained.
Furthermore, by subjecting the surface of the metal foil substrate 1 to an alkali treatment, the surface is moderately roughened and a coating film of a silane coupling agent is easily attached, and strong adhesion can be maintained.

  Examples of the present invention will be described below.

<Example 1>
An aluminum foil having a thickness of 7 μm was used as the metal foil base material. Then, the surface of the metal foil substrate was subjected to an alkali cleaning treatment with a 1% NaCO ₃ solution.
Next, a thin film of an ethyl acetate solution of an isocyanate type silane coupling agent with a solid content of 5 wt% was applied on the alkali-cleaned surface so that the coating amount after drying was 0.5 g / m ² or less. Furthermore, the coating amount after drying a thin film of a coating solution containing no polyol and containing a biuret type of hexamethylene diisocyanate so that the solid content ratio is 2.5 wt% is 0.5 g / m ² or less. An anchor coat layer and an adhesive layer were sequentially provided.
Then, a linear low density polyethylene film (thickness 40 μm) was bonded onto the adhesive layer to provide a sealant layer, and then an aging treatment was performed to obtain a laminate according to Example 1. The thickness of the adhesive layer after drying was 0.05 μm.

<Example 2>
Except that low-density polyethylene was extruded from an extruder in a molten state and laminated on the adhesive layer, and a linear low-density polyethylene film (thickness 40 μm) was laminated on the extruded resin layer to provide a sealant layer. A laminate according to Example 2 was obtained in the same manner as in Example 1.

<Example 3>
A laminate according to Example 3 was obtained in the same manner as in Example 1 except that a sealant layer made of an ethylene-propylene copolymer was bonded onto the adhesive layer.

<Comparative Example 1>
An aluminum foil having a thickness of 7 μm was used as the metal foil base material. And the surface of this metal foil base material was subjected to an alkali cleaning treatment with a 1% NaCO ₃ solution.
Next, on the alkali cleaning treatment, a thin film of an ethyl acetate solution of an isocyanate type silane coupling agent having a solid content of 5 wt% was applied so that the coating amount after drying was 0.5 g / m ² or less, Furthermore, a thin film of a coating solution in which a polyester polyol as a polyol and an adduct type of tolylene diisocyanate as an isocyanate compound are mixed so that a weight ratio of polyol: isocyanate compound = 75: 25 is applied, and an anchor coat layer and an adhesive layer are sequentially formed. Provided.
And the sealant layer which consists of a linear low density polyethylene film (40 micrometers in thickness) was laminated | stacked on the contact bonding layer, and the laminated body which concerns on the comparative example 1 was obtained.

<Comparative Example 2>
The same as in Example 1 except that the anchor coat layer was not provided and the adhesive layer made of the polyisocyanate compound was directly provided on the 7 μm thick aluminum foil base material whose surface was subjected to alkali cleaning treatment with 1% NaCO ₃ solution. The laminated body which concerns on the comparative example 2 was obtained by the method.

<Comparative Example 3>
A 7 μm thick aluminum foil was used as the metal foil base material, and a thin film of an ethyl acetate solution of an aisocyanate-type silane coupling agent was applied to the surface without any surface treatment. Comparative Example 3 in the same manner as in Example 1 except that a thin film of a coating solution having a solid content ratio of 2.5 wt% was applied to the biuret type and an anchor coat layer and an adhesive layer were sequentially provided. The laminated body which concerns on was obtained.

  After performing aging for 5 days at 50 degreeC to each laminated body of Examples 1-3 obtained by making it above, and Comparative Examples 1-3, the pouch was produced using each laminated body. And after filling limonene liquid (volatile strong osmotic substance) and bathing agent (containing a fragrance component and alcohol as volatile strong osmotic substance) into each pouch 150 g each, and sealing, It was left in a constant temperature room at 40 ° C.

  After the elapse of 3 months, these pouches were taken out from the thermostatic chamber, and the laminate strength [N / 15 mm] between the aluminum foil base material and the sealant layer of each pouch was measured, and compared with the laminate strength in the pouch before entering the thermostatic chamber. The measurement conditions of the laminate strength at this time were T-type peeling with a sample width of 15 mm and a peeling speed of 300 mm / min. In addition, the change in the weight of the content of the bath preparation was measured. Table 1 summarizes the measurement results before and after entering the temperature-controlled room.

  It was found that the laminates according to Examples 1 to 3 had excellent laminate strength, and the laminate strength between the metal foil base material and the sealant layer did not decrease even when a strong penetrating substance containing a volatile component acts. .

  Further, the laminate of the present invention includes a metal foil base material, an anchor coat layer made of a silane coupling agent, an adhesive layer made of an isocyanate compound, a polyethylene resin, a polypropylene resin, or an ethylene-propylene copolymer. The sealant layer is composed of at least four layers, and the anchor coat layer firmly adheres to the surface of the alkali-treated metal foil base, and the adhesive layer is not affected by the strongly permeable content. Since it consists of a very thin and dense layer, it showed excellent laminate strength against the metal foil substrate.

Further, since the adhesive layer is composed of an isocyanate compound, the adhesive layer is hardly deteriorated with respect to the highly permeable material and has high resistance.
Furthermore, when the adhesive layer has a thickness of 0.01 μm or more, the strength of the laminate itself is increased, and it is possible to make it easy to cut due to the stiffness.

  Further, the polyurethane compound constituting the adhesive layer is synthesized from a bifunctional isocyanate monomer or a derivative of a trifunctional monomer of adduct, biuret, or isocyanurate type, whereby an isocyanate compound is It was possible to have a structure having a urea bond with high content resistance, and as a result, it was possible to obtain a laminate in which the laminate strength was not lowered by a strong permeable material containing a volatile component.

DESCRIPTION OF SYMBOLS 1 ... Metal foil base material 2 ... Anchor coat layer 3 ... Adhesive layer 4 ... Sealant layer

Claims (5)

  A laminate comprising an anchor coat layer made of a silane coupling agent, an adhesive layer made of an isocyanate compound, and a sealant layer provided in this order on the surface of the metal foil substrate.   The laminate according to claim 1, wherein the sealant layer is made of any one of a polyethylene resin, a polypropylene resin, and an ethylene-propylene copolymer.   The constituent material of the adhesive layer is synthesized from a bifunctional isocyanate monomer or a derivative of a trifunctional monomer of adduct, biuret or isocyanurate type. Laminated body.   The laminate according to any one of claims 1 to 3, wherein the adhesive layer has a thickness of 0.01 µm to 1 µm.   The laminate according to any one of claims 1 to 4, wherein the surface of the metal foil substrate is subjected to a cleaning treatment with an alkali.

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